CN217594316U - Cleaning device for ion exchange membrane in electrodialysis membrane stack - Google Patents
Cleaning device for ion exchange membrane in electrodialysis membrane stack Download PDFInfo
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Abstract
The utility model relates to an ion exchange membrane's belt cleaning device in electrodialysis membrane stack, the device include wash liquor case, built-in electrodialysis membrane stack and the rectifier of waiting to wash ion exchange membrane, the wash liquor case still connect water tank, sour explosive box, metal ion complexing agent explosive box, alkali explosive box, hydrogen peroxide explosive box and surfactant active explosive box respectively through the charge-in pipeline, the export of wash liquor case still draw forth two branches and connect respectively through liquid outlet pipe the entry and the export of electrodialysis membrane stack, electrodialysis membrane stack both ends are still connected the two poles of the earth of rectifier. Compared with the prior art, the utility model discloses improve the current ion exchange membrane and wash only adopt single chemical reagent to wash, the problem that the cleaning efficiency is low, the membrane performance declines gradually.
Description
Technical Field
The utility model belongs to the technical field of the membrane washs, a ion exchange membrane's belt cleaning device in electrodialysis membrane stack is related to.
Background
The ion exchange membrane is a material with a unique selective permeability function, can effectively separate each component in fluid under the drive of an electric field, and is widely applied to the fields of seawater desalination, wastewater zero discharge, landfill leachate treatment, reclaimed water reuse, chemical wastewater treatment, material separation, purification, concentration and the like.
In the process of electrodialysis operation, various inorganic matters, microorganisms, organic matters and oils in raw water are concentrated and enriched on the surface of the membrane, and dirt blocks the surface of the membrane and even membrane pores, so that the desalination rate is reduced, the membrane pollution is serious and inevitable, and chemical cleaning is an effective method for recovering the membrane flux. However, researches show that irreversible decline (namely 'membrane aging') can occur to the membrane chemical stability and the filtration performance after long-term chemical cleaning, the service life of the membrane is shortened, the stable operation of the membrane is influenced, the operation cost is increased, and the further popularization and application of the electrodialysis technology are restricted. Therefore, the development of a green and efficient cleaning technology is urgently needed, which not only can meet the membrane cleaning requirement, but also can correctly control the membrane aging process.
At present, the membrane cleaning agent existing in the market is only applied to a certain pollutant or a certain class of pollutants (such as oil or organic matters), and the application scene is narrow. For complex composite pollution caused by oil, organic matters and inorganic matters at the same time, the effect is often not good only by chemical cleaning. The present invention is also based on this.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an ion exchange membrane's belt cleaning device and method in electrodialysis membrane stack aims at improving the current ion exchange membrane and washs and only adopt single chemical reagent to wash, the problem that the cleaning efficiency is low, the membrane performance declines gradually.
The purpose of the utility model can be realized by the following technical proposal:
one of the technical proposals of the utility model provides a cleaning device of an ion exchange membrane in an electrodialysis membrane stack, which comprises a cleaning fluid box, the electrodialysis membrane stack internally provided with the ion exchange membrane to be cleaned and a rectifier,
the cleaning solution box is further respectively connected with a water tank, an acid medicine storage box, a metal ion complexing agent medicine storage box, an alkali medicine storage box, a hydrogen peroxide medicine storage box and a surfactant medicine storage box through a feeding pipeline, the outlet of the cleaning solution box is also led out two branches through a liquid outlet pipeline and respectively connected with the inlet and the outlet of the electrodialysis membrane stack, and the two ends of the electrodialysis membrane stack are also connected with the two poles of the rectifier. Two poles of the rectifier are respectively connected with the ports of the electrodialysis membrane stack so as to apply equidirectional electricity or reverse electricity to the electrodialysis membrane stack (the equidirectional electricity is that the current direction is from the positive electrode to the negative electrode of the electrodialysis, and the reverse electricity is that the current direction is changed so that the positive electrode and the negative electrode of the electrodialysis are reversed).
Furthermore, a discharge pump is further arranged on the liquid outlet pipeline, and stop valves are further respectively arranged on branches connected with the inlet and the outlet of the electrodialysis membrane stack.
Furthermore, a filter and a micro-nano bubble generator are arranged on a branch path connected with the inlet of the electrodialysis membrane stack. Through strengthening chemical cleaning with micro-nano bubble technology, can high-efficiently get rid of remain at ion exchange membrane surface and the downthehole all kinds of pollutants of membrane, improve ion exchange membrane's desalination, guarantee ion exchange membrane's steady operation.
Further, the filter has a filtration accuracy of less than 10 microns.
Furthermore, a circulating cleaning pump is arranged on a branch connected with the inlet or the outlet of the electrodialysis membrane stack.
Furthermore, a stirrer is further arranged in the cleaning liquid tank.
Furthermore, the inlet of the electrodialysis membrane stack comprises a material inlet, an electrode chamber inlet and a concentration chamber inlet during desalination of the electrodialysis membrane stack, the outlet of the electrodialysis membrane stack comprises a material outlet, an electrode chamber outlet and a concentration chamber outlet during desalination of the electrodialysis membrane stack, and each inlet and each outlet are respectively connected into a branch of the electrodialysis membrane stack through an independently controlled stop valve.
The second technical proposal of the utility model provides a cleaning method of an ion exchange membrane in an electrodialysis membrane stack, which is based on the cleaning device, the cleaning method comprises water cleaning, primary acid cleaning, alkali cleaning and secondary acid cleaning which are carried out in sequence, wherein,
the water cleaning process specifically comprises the following steps: and (3) delivering the water in the water tank into a cleaning fluid tank, pumping into the electrodialysis membrane stack, circularly cleaning, and discharging, wherein the temperature during circular cleaning is preferably 25-35 ℃, and the time for circular cleaning is 20-30 min, so as to obtain the water-washed membrane.
The primary pickling process comprises the following specific steps: pumping water in a water tank, an acidic reagent in an acid medicine storage tank and a metal ion complexing agent in a metal ion complexing agent medicine storage tank into a cleaning liquid tank, stirring, pumping into an electrodialysis membrane stack, circularly cleaning and discharging to finish. Specifically, the time of circulating cleaning is 60-90 min, the pH value of the cleaning solution in the primary acid cleaning process is controlled to be 2-3, and the content of the metal ion complexing agent is 0.2-2 wt%. The acidic cleaning agent used for adjusting the pH can be hydrochloric acid, oxalic acid or citric acid, etc. The metal ion complexing agent can be disodium ethylene diamine tetraacetate.
The alkali washing process specifically comprises the following steps: pumping water in a water tank, an alkaline reagent in an alkaline medicine storage tank, hydrogen peroxide in a hydrogen peroxide medicine storage tank and a surfactant in a surfactant medicine storage tank into a cleaning liquid tank, stirring, pumping into an electrodialysis membrane stack, circularly cleaning and discharging to finish. Specifically, the time of alkali washing is 60-90 min. The pH value of the alkaline cleaning solution is preferably 11-12, and the alkaline reagent used for adjusting the pH value can be sodium hydroxide or sodium carbonate. The surfactant is preferably sodium dodecyl benzene sulfonate and/or sodium dodecyl sulfate, and more preferably, the content of the sodium dodecyl benzene sulfonate in the alkaline cleaning solution is 0.05-0.1wt%, and the content of the sodium dodecyl sulfate in the alkaline cleaning solution is 0.05-0.1wt%. The content of hydrogen peroxide is 5-10wt%.
The secondary pickling process specifically comprises the following steps: pumping water in the water tank and an acidic reagent in the acid medicine storage tank into a cleaning liquid tank, stirring, pumping into the electrodialysis membrane stack, circularly cleaning, and discharging to finish. Similarly, the pH of the cleaning solution with secondary acidity is controlled to be 2-3, and the acidic reagent can be hydrochloric acid, oxalic acid or citric acid.
Through repeated research, the components and the contents in the acidic cleaning solution and the alkaline cleaning solution are selected, the cleaning effect is not ideal when the using amount of each component of the acidic cleaning solution and the alkaline cleaning solution is too high or too low, the desalination rate of the ion exchange membrane can be obviously improved within the range, the resistance of the ion exchange membrane is reduced, and the stable operation of an electrodialysis system is ensured. An additional acid wash is added after the alkaline wash in order to restore the change in ion exchange membrane exchange groups caused by the alkaline wash.
Further, one or the combination of two of the processes of forward washing and back washing is independently adopted in water washing, primary acid washing, alkali washing and secondary acid washing respectively, wherein,
the forward washing process is to control the washing liquid in the circulating washing process to enter from the inlet of the electrodialysis membrane stack and then to be discharged from the outlet of the electrodialysis membrane stack, and the process is circulated;
and the backwashing process is to control the cleaning liquid in the circulating cleaning process to enter from the outlet of the electrodialysis membrane stack and then to be discharged from the inlet of the electrodialysis membrane stack, and the circulation is carried out.
Further, in the primary acid washing process, the rectifier is started and used for applying equidirectional electricity to the electrodialysis membrane stack;
during the alkaline washing process, the rectifier is turned on and used to apply a reverse current to the electrodialysis membrane stack.
The utility model discloses a micro-nano bubble and chemical agent's synergism has not only increased the area of contact of chemical agent and pollutant, and its self also promotes organic pollutant's analysis because of high interface charge, cavitation production active oxygen and pollutant effect, reduces chemical agent's use amount.
Drawings
Fig. 1 is a schematic structural diagram of an ion exchange membrane cleaning device according to the present invention.
The notation in the figure is:
the device comprises a 1-acid medicine storage box, a 2-metal ion complexing agent medicine storage box, a 3-alkali medicine storage box, a 4-hydrogen peroxide medicine storage box, a 5-surfactant medicine storage box, a 6-water tank, a 7-stirrer, an 8-cleaning liquid box, a 9-water pump, a 10-medicine feeding pump, an 11-discharging pump, a 12-filter, a 13-micro-nano bubble generator, a 14-electrodialysis membrane stack, a 15-rectifier and a 16-circulation cleaning pump.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and specific embodiments. The embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Electrodialysis pollution is mainly divided into inorganic pollution and organic pollution, wherein the inorganic pollution is caused by that high-salinity wastewater contains a large amount of calcium and magnesium ions which react with sulfate radicals, hydroxyl radicals and carbonate radicals in a solution to form scale on the surface of an ion exchange membrane, so that voltage is increased, and normal operation is influenced. Most of the organic matters are electronegative and are accumulated on the surface of an anion exchange membrane or enter the anion exchange membrane during the operation process of electrodialysis, so that organic pollution is caused. Ordinary acid, alkali wash usually can wash the scale deposit on ion exchange membrane surface, organic deposit, the inside partial scale deposit of positive membrane on the one hand, the inside organic pollution of negative membrane can not be solved, can lead to the pollutant accumulation in the ion exchange membrane more and more, make the life-span of ion exchange membrane significantly reduce, on the other hand, the ion exchange group of ion exchange membrane can change after alkali wash, for example the quaternary ammonium group of negative membrane can change into tertiary ammonium group, this can seriously influence ion exchange membrane's desalination ability.
In order to solve at least one of the above problems, the present invention provides a novel method and apparatus for cleaning an electrodialysis membrane stack 14.
The utility model provides a cleaning device for an ion exchange membrane in an electrodialysis membrane stack, which is shown in figure 1 and comprises a cleaning solution box 8, an electrodialysis membrane stack 14 with an ion exchange membrane to be cleaned arranged inside, and a rectifier 15,
the cleaning solution box 8 is further respectively connected with a water tank 6, an acid medicine storage box 1, a metal ion complexing agent medicine storage box 2, an alkali medicine storage box 3, a hydrogen peroxide medicine storage box 4 and a surfactant medicine storage box 5 through a feeding pipeline, the outlet of the cleaning solution box 8 is further led out of two branches through a liquid outlet pipeline and is respectively connected with the inlet and the outlet of the electrodialysis membrane stack 14, and two ends of the electrodialysis membrane stack 14 are further connected with two poles of a rectifier 15. The two poles of the rectifier 15 are respectively connected with the ports of the electrodialysis membrane stack 14, so as to apply the same direction electricity or reverse direction electricity to the electrodialysis membrane stack 14 (the same direction electricity, namely the current direction, is from the positive pole to the negative pole of the electrodialysis, and the reverse direction electricity, namely the current direction is changed, so that the positive pole and the negative pole of the electrodialysis are reversed).
In some specific embodiments, the liquid outlet pipeline is further provided with a discharge pump 11, and the branches connecting the inlet and the outlet of the electrodialysis membrane stack 14 are further provided with a stop valve respectively.
In some specific embodiments, a filter 12 and a micro-nano bubble generator 13 are further disposed on a branch connecting an inlet of the electrodialysis membrane stack 14. Through strengthening chemical cleaning with micro-nano bubble technology, can high-efficiently get rid of remain at ion exchange membrane surface and the downthehole all kinds of pollutants of membrane, improve ion exchange membrane's desalination, guarantee ion exchange membrane's steady operation.
Further, the filter 12 has a filtration accuracy of less than 10 microns.
In some specific embodiments, a circulation cleaning pump 16 is further arranged on a branch connected with the inlet or the outlet of the electrodialysis membrane stack 14.
In some embodiments, the washing liquid tank 8 is further provided with an agitator 7.
In some specific embodiments, the inlets of the electrodialysis membrane stack 14 include a material inlet, an electrode compartment inlet and a concentration compartment inlet when the electrodialysis membrane stack 14 is operated for desalination, and the outlets of the electrodialysis membrane stack 14 include a material outlet, an electrode compartment outlet and a concentration compartment outlet when the electrodialysis membrane stack 14 is operated for desalination, and each inlet and each outlet are respectively connected into a branch of the electrodialysis membrane stack 14 through a stop valve which is controlled independently.
The utility model also provides a cleaning method of the ion exchange membrane in the electrodialysis membrane stack, which is based on the cleaning device, the cleaning method comprises water cleaning, primary acid cleaning, alkali cleaning and secondary acid cleaning which are carried out in sequence, wherein,
the water cleaning process specifically comprises the following steps: and (3) delivering the water in the water tank 6 into a cleaning solution tank 8, pumping into the electrodialysis membrane stack 14, circularly cleaning, and discharging, wherein the temperature during circular cleaning is preferably 25-35 ℃, and the time for circular cleaning is 20-30 min, so as to obtain the water-washed membrane.
The primary pickling process comprises the following specific steps: pumping the water in the water tank 6, the acidic reagent in the acid medicine storage tank 1 and the metal ion complexing agent in the metal ion complexing agent medicine storage tank 2 into a cleaning solution tank 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning and discharging to finish. Specifically, the time of circulating cleaning is 60-90 min, the pH value of the cleaning solution in the primary acid cleaning process is controlled to be 2-3, and the content of the metal ion complexing agent is 0.2-2 wt%. The acidic cleaning agent used for adjusting the pH can be hydrochloric acid, oxalic acid or citric acid, etc. The metal ion complexing agent may be disodium edetate.
The alkali washing process specifically comprises the following steps: pumping water in the water tank 6, an alkaline reagent in the alkaline medicine storage box 3, hydrogen peroxide in the hydrogen peroxide medicine storage box 4 and a surfactant in the surfactant medicine storage box 5 into the cleaning liquid box 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning and discharging to finish. Specifically, the time of alkali washing is 60-90 min. The pH value of the alkaline cleaning solution is preferably 11-12, and the alkaline reagent used for adjusting the pH value can be sodium hydroxide or sodium carbonate. The surfactant is preferably sodium dodecyl benzene sulfonate and/or sodium dodecyl sulfate, and more preferably, the content of the sodium dodecyl benzene sulfonate in the alkaline cleaning solution is 0.05-0.1wt%, and the content of the sodium dodecyl sulfate in the alkaline cleaning solution is 0.05-0.1wt%. The content of hydrogen peroxide is 5-10wt%.
The secondary acid washing process comprises the following specific steps: pumping the water in the water tank 6 and the acid reagent in the acid medicine storage tank 1 into the cleaning liquid tank 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning, and discharging to finish. Similarly, the pH of the cleaning solution with secondary acidity is controlled to be 2-3, and the acidic reagent can be hydrochloric acid, oxalic acid or citric acid.
Through repeated research, the components and the contents in the acidic cleaning solution and the alkaline cleaning solution are selected, and the cleaning effect is not ideal when the consumption of the components in the acidic cleaning solution and the alkaline cleaning solution is too high or too low, so that the desalination rate of the ion exchange membrane can be obviously improved, the resistance of the ion exchange membrane is reduced, and the stable operation of an electrodialysis system is ensured. An additional acid wash is added after the alkaline wash to restore the change in ion exchange membrane exchange groups caused by the alkaline wash.
In some embodiments, one or a combination of two forward washing and reverse washing processes are independently used in the water washing, the primary acid washing, the alkali washing and the secondary acid washing respectively, wherein,
the forward washing process is to control the washing liquid in the circulating washing process to enter from the inlet of the electrodialysis membrane stack 14 and then to be discharged from the outlet of the electrodialysis membrane stack, and the circulation is carried out;
the backwashing process is to control the cleaning liquid in the circulating cleaning process to enter from the outlet of the electrodialysis membrane stack 14 and then to be discharged from the inlet of the electrodialysis membrane stack, and the circulation is carried out.
Further, in the primary acid washing process, the rectifier 15 is turned on and is used for applying the same-direction electricity to the electrodialysis membrane stack 14;
during the alkaline washing process, the rectifier 15 is turned on and used to apply a reverse current to the electrodialysis membrane stack 14.
In the electrodialysis operation process, the generated inorganic scaling reaction is mainly concentrated in a concentration chamber and a polar chamber, and organic matter pollution is mainly generated on the surface (a dilute chamber or a material chamber side) or inside an anion exchange membrane.
And on one hand, the disodium ethylene diamine tetraacetate can complex calcium and magnesium metal ions to weaken the compactness of inorganic dirt, and then hydrogen ions permeate the cationic membrane to clean magnesium hydroxide or calcium hydroxide precipitate generated by hydroxyl generated by electrolysis in membrane pores in the migration process of calcium and magnesium, and forward washing and backwashing can clean scales generated on the surfaces of the cationic membrane and the polar chamber.
The alkali wash process can be through reverse circular telegram, make the dense-dilute room exchange, the hydroxyl can see through the negative membrane from original dense-dilute room and migrate to the dilute room, simultaneously because the existence of hydrogen peroxide and surfactant, can realize degrading, dissolving, peeling off and cleaing away organic pollutant with three's synergistic effect, and then accomplish the recovery to polluting the membrane performance in the short time, have high efficiency, convenient, the weak point's of consuming time advantage.
And a step of acid washing is added after the alkali washing, so that the ion groups on the ion exchange membrane are changed after the alkali washing, and the desalting performance of the ion exchange membrane can be recovered after the acid washing. Meanwhile, the cleaning process is always accompanied with the cooperative operation of the micro-nano bubble generator 13, the high mass transfer efficiency of the micro-nano bubbles not only improves the utilization rate of chemical agents, but also can generate hydroxyl radicals when the bubbles collapse, so that the hydroxyl radicals can indirectly and non-selectively react with organic pollutants, and the synergistic effect of the hydroxyl radicals and the chemical agents also promotes the degradation rate of the pollutants. Based on this, the utility model provides a with micro-nano bubble and chemical cleaning agent collaborative work, the ageing process of control film on reaching the basis of wasing efficiency, and then release a novel cleaning technology. The cleaning method can solve the problem of membrane surface and internal pollution, recover the membrane performance, and reduce the period of membrane replacement, thereby reducing the operation cost.
The following describes the method and apparatus for cleaning the electrodialysis membrane stack 14 in detail with reference to the accompanying drawings and specific examples.
Example 1:
the embodiment provides a cleaning device for an ion exchange membrane in an electrodialysis membrane stack, please refer to fig. 1, which includes a cleaning solution tank 8, an electrodialysis membrane stack 14 with an ion exchange membrane to be cleaned inside, and a rectifier 15,
the cleaning solution box 8 is also respectively connected with a water tank 6, an acid medicine storage box 1, a metal ion complexing agent medicine storage box 2, an alkali medicine storage box 3, a hydrogen peroxide medicine storage box 4 and a surfactant medicine storage box 5 through a feeding pipeline, the outlet of the cleaning solution box 8 is also led out of two branches through a liquid outlet pipeline and is respectively connected with the inlet and the outlet of the electrodialysis membrane stack 14, and two ends of the electrodialysis membrane stack 14 are also connected with two electrodes of the rectifier 15.
Referring to fig. 1 again, the liquid outlet pipeline is further provided with a discharge pump 11, and branch paths connecting an inlet and an outlet of the electrodialysis membrane stack 14 are further respectively provided with a stop valve. A water pump 9 is arranged between the water tank 6 and the cleaning liquid tank 8, and a dosing pump 10 is arranged between each medicine storage tank and the cleaning liquid tank 8. And a circulating cleaning pump 16 is also arranged on a branch connected with the inlet or the outlet of the electrodialysis membrane stack 14, and a circulating cleaning loop for the electrodialysis membrane stack 14 is formed by the circulating cleaning pump 16 and the two branches connected with the electrodialysis membrane stack 14 in a matching manner.
Meanwhile, the discharge pump 11, the water pump 9, the dosing pump 10 and the like in the embodiment can all adopt fluoroplastic chemical pumps.
And a filter 12 and a micro-nano bubble generator 13 are also arranged on a branch path connected with the inlet of the electrodialysis membrane stack 14. Chemical cleaning is enhanced by the micro-nano bubble technology, various pollutants remained on the surface of the ion exchange membrane and in the membrane hole can be efficiently removed, the desalination rate of the ion exchange membrane is improved, and the stable operation of the ion exchange membrane is ensured. The filter 12 has a filtration accuracy of less than 10 microns. And a stirrer 7 is also arranged in the cleaning liquid tank 8.
The inlet of the electrodialysis membrane stack 14 comprises a material inlet, an electrode chamber inlet and a concentration chamber inlet during desalination operation of the electrodialysis membrane stack 14, the outlet of the electrodialysis membrane stack 14 comprises a material outlet, an electrode chamber outlet and a concentration chamber outlet during desalination operation of the electrodialysis membrane stack 14, and each inlet and each outlet are respectively connected into a branch of the electrodialysis membrane stack 14 through an independently controlled stop valve.
The embodiment also provides a cleaning method of an ion exchange membrane in an electrodialysis membrane stack, which is based on the cleaning device, and the cleaning method comprises water cleaning, primary acid cleaning, alkali cleaning and secondary acid cleaning which are sequentially carried out, wherein,
the water cleaning process specifically comprises the following steps: and (3) feeding water in the water tank 6 into a cleaning solution tank 8, pumping into the electrodialysis membrane stack 14, circularly cleaning, and discharging, wherein the temperature during circular cleaning is preferably 30 ℃, and the time for circular cleaning is 25min to obtain the water-washed membrane.
The primary pickling process comprises the following specific steps: pumping the water in the water tank 6, the acidic reagent in the acid medicine storage tank 1 and the metal ion complexing agent in the metal ion complexing agent medicine storage tank 2 into a cleaning solution tank 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning and discharging to finish. Specifically, the time of circulating cleaning is 78min, the pH value of the cleaning solution in the primary acid cleaning process is controlled to be about 2.5, and the content of the metal ion complexing agent is 1wt%. And the acidic cleaning agent used for adjusting the pH value can be oxalic acid. The metal ion complexing agent is disodium ethylene diamine tetraacetate.
The alkali washing process specifically comprises the following steps: pumping water in the water tank 6, an alkaline reagent in the alkaline medicine storage box 3, hydrogen peroxide in the hydrogen peroxide medicine storage box 4 and a surfactant in the surfactant medicine storage box 5 into the cleaning liquid box 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning and discharging to finish. Specifically, the time of alkaline washing is 75min. The pH value of the alkaline cleaning solution is preferably about 11 to 12, and sodium hydroxide is used as an alkaline reagent for adjusting the pH value. The surfactant is preferably sodium dodecyl benzene sulfonate and sodium dodecyl sulfate, and meanwhile, in the alkaline cleaning solution, the content of the sodium dodecyl benzene sulfonate is 0.08wt%, and the content of the sodium dodecyl sulfate is 0.08wt%. The hydrogen peroxide content was 8wt%.
The secondary acid washing process comprises the following specific steps: pumping the water in the water tank 6 and the acid reagent in the acid medicine storage tank 1 into the cleaning liquid tank 8, stirring, pumping into the electrodialysis membrane stack 14, circularly cleaning, and discharging to finish. Similarly, the pH of the cleaning solution with secondary acidity is controlled to be 2.5, and the acidic reagent can be hydrochloric acid.
Through repeated research, the components and the contents in the acidic cleaning solution and the alkaline cleaning solution are selected, and the cleaning effect is not ideal when the consumption of the components in the acidic cleaning solution and the alkaline cleaning solution is too high or too low, so that the desalination rate of the ion exchange membrane can be obviously improved, the resistance of the ion exchange membrane is reduced, and the stable operation of an electrodialysis system is ensured. An additional acid wash is added after the alkaline wash to restore the change in ion exchange membrane exchange groups caused by the alkaline wash.
One or the combination of two of forward washing and back washing is independently adopted in water washing, primary acid washing, alkali washing and secondary acid washing respectively, wherein,
the forward washing process is to control the washing liquid in the circulating washing process to enter from the inlet of the electrodialysis membrane stack 14 and then to be discharged from the outlet of the electrodialysis membrane stack, and the circulation is carried out; specifically, referring to fig. 1, through valve cutoff, the prepared cleaning solution is pumped into a filter 12, the cleaning solution is filtered by the 10um filter 12 and then enters a micro-nano bubble generator 13, a large amount of micro-nano bubbles are generated and pumped into an inlet of an electrodialysis membrane stack 14 along with the cleaning solution, at this time, each stop valve arranged at the inlet of the electrodialysis membrane stack 14 is opened, that is, the cleaning solution flows into the membrane stack from outlets of a material, a polar chamber and a concentration chamber during desalination operation of the membrane stack, and then each stop valve at the outlet of the electrodialysis membrane stack 14 is opened, that is, the cleaning solution flows out of the membrane stack from outlets of the material, the polar chamber and the concentration chamber during desalination operation of the membrane stack, and then the cleaning solution is recycled in the electrodialysis membrane stack 14 through a circulation loop and a circulation cleaning pump 16 formed by two branches. The remaining non-mentioned valves are closed. And the washing is finished and the washing can be discharged by opening the discharge valve.
The backwashing process is to control the cleaning liquid in the circulating cleaning process to enter from the outlet of the electrodialysis membrane stack 14 and then to be discharged from the inlet of the electrodialysis membrane stack, and the circulation is carried out. Specifically, the prepared cleaning solution is pumped into a circulating cleaning pump 16, a valve at the outlet of an electrodialysis membrane stack 14 is opened, the cleaning solution enters a material, a polar chamber and a concentration chamber during desalination operation of the membrane stack, and then the valve at the inlet of the electrodialysis membrane stack 14 is opened, namely the cleaning solution flows out of the membrane stack from the material, the polar chamber and the concentration chamber during desalination operation of the membrane stack, is filtered by a micro-nano bubble generator 13 and a 10um filter 12, and is recycled in the electrodialysis membrane stack 14 through a circulating loop formed by two branches and the circulating cleaning pump 16. The remaining non-mentioned valves are closed. After the cleaning is finished, the cleaning liquid can be discharged by opening a discharge valve.
In addition, the rectifier 15 is turned on and used to apply a co-current to the electrodialysis membrane stack 14 for 60s during one acid wash cycle for 10 cycles.
During the alkaline washing process, the rectifier 15 is turned on and used to apply a reverse current to the electrodialysis membrane stack 14 for 60s, with 10 cycles. During the secondary pickling process, the rectifier 15 does not need to be opened.
Example 2
After an electrodialysis membrane module for treating desulfurization wastewater of a power plant continuously runs for one month, serious irreversible pollution is generated, the desalination rate is reduced by 50%, and the device and the process method in the embodiment 1 are utilized for cleaning. Evaluation of cleaning performance: measuring the salt rejection rate;
under the same measurement conditions, the salt rejection rates of the ion exchange membranes after the untreated desulfurization waste water, the treated desulfurization waste water, and the cleaning were measured, respectively.
Comparative example 1:
compared with the embodiment 2, most of the cleaning steps are the same, and the functional part of the micro-nano bubble generator is omitted. The cleaning performance was evaluated in the same manner as in example 2.
Comparative example 2:
compared with the embodiment 2, most cleaning steps are the same, and the procedure of secondary acid cleaning is omitted. The cleaning performance was evaluated in the same manner as in example 2.
The results of evaluating the cleaning performance of example 2 and comparative examples 1 to 2 are shown in table 1.
TABLE 1 evaluation of cleaning Performance of example 2 and comparative examples 1 to 2
| D1 | D2 | D3 | Recovery ratio (%) | |
| Example 2 | 96.2 | 45.7 | 95.1 | 98.8 |
| Comparative example 1 | 96.2 | 46.1 | 75.9 | 78.9 |
| Comparative example 2 | 96.2 | 45.2 | 69.6 | 72.3 |
Remarking: d1 (%): the desalination rate of the ion exchange membrane without performing electrodialysis treatment on the desulfurization wastewater; d2 (%): the desalination rate of the ion exchange membrane for performing electrodialysis treatment on the desulfurization wastewater;
d3 (%): carrying out electrodialysis treatment on the desulfurization wastewater and the desalination rate of the cleaned ion exchange membrane;
recovery (%) = D3/D1 x 100%
The embodiments described above are intended to facilitate the understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention according to the disclosure of the present invention.
Claims (8)
1. A cleaning device for an ion exchange membrane in an electrodialysis membrane stack is characterized by comprising a cleaning solution box, the electrodialysis membrane stack internally provided with the ion exchange membrane to be cleaned and a rectifier,
the cleaning solution box is further respectively connected with a water tank, an acid medicine storage box, a metal ion complexing agent medicine storage box, an alkali medicine storage box, a hydrogen peroxide medicine storage box and a surfactant medicine storage box through a feeding pipeline, the outlet of the cleaning solution box is also led out two branches through a liquid outlet pipeline and respectively connected with the inlet and the outlet of the electrodialysis membrane stack, and the two ends of the electrodialysis membrane stack are also connected with the two poles of the rectifier.
2. The device for cleaning the ion exchange membrane in the electrodialysis membrane stack according to claim 1, wherein a discharge pump is further disposed on the liquid outlet pipeline, and stop valves are further disposed on branches connecting the inlet and the outlet of the electrodialysis membrane stack, respectively.
3. The device for cleaning the ion exchange membrane in the electrodialysis membrane stack as claimed in claim 1, wherein a filter and a micro-nano bubble generator are further provided on a branch connecting the inlet of the electrodialysis membrane stack.
4. A cleaning device for ion exchange membranes in electrodialysis membrane stack according to claim 3, wherein the filtration precision of the filter is less than 10 μm.
5. The device for cleaning the ion exchange membranes in the electrodialysis membrane stack as claimed in claim 1, wherein a circulation cleaning pump is further provided on a branch connecting the inlet or the outlet of the electrodialysis membrane stack.
6. An apparatus for cleaning ion exchange membranes in electrodialysis membrane stack according to claim 1, wherein the cleaning solution tank is further provided with a stirrer.
7. The device for cleaning the ion exchange membrane in the electrodialysis membrane stack as claimed in claim 1, wherein the inlet of the electrodialysis membrane stack comprises a material inlet, an electrode compartment inlet and a concentration compartment inlet during desalination operation of the electrodialysis membrane stack, and the outlet of the electrodialysis membrane stack comprises a material outlet, an electrode compartment outlet and a concentration compartment outlet during desalination operation of the electrodialysis membrane stack.
8. An apparatus for cleaning ion exchange membranes in electrodialysis membrane stacks as claimed in claim 7, wherein each inlet and each outlet are connected to a branch of the electrodialysis membrane stack via independently controlled shut-off valves.
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| CN202220498904.1U CN217594316U (en) | 2022-03-09 | 2022-03-09 | Cleaning device for ion exchange membrane in electrodialysis membrane stack |
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| CN202220498904.1U CN217594316U (en) | 2022-03-09 | 2022-03-09 | Cleaning device for ion exchange membrane in electrodialysis membrane stack |
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