CN115626686A

CN115626686A - Cleaning system and cleaning method for ultrapure water equipment

Info

Publication number: CN115626686A
Application number: CN202210848270.2A
Authority: CN
Inventors: 巩泉雨; 区灿林; 周维
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd; BYD Auto Co Ltd
Priority date: 2022-07-19
Filing date: 2022-07-19
Publication date: 2023-01-20
Anticipated expiration: 2042-07-19
Also published as: CN115626686B

Abstract

The application provides a cleaning system and a cleaning method of ultrapure water equipment. This cleaning system has set up liquid medicine liquid storage cylinder and the pipeline of matcing with it at reverse osmosis module and EDI module respectively for reverse osmosis module can possess the pickling process, EDI module can possess the acid-base and synthesize the cleaning process, can fully clean the core module of ultrapure water equipment, thereby can guarantee that the inside cleanliness factor of core module is higher, improve the quality stability of producing water, prolong the life of core module.

Description

Cleaning system and cleaning method for ultrapure water equipment

Technical Field

The application relates to the technical field of water treatment, in particular to a cleaning system and a cleaning method of ultrapure water equipment.

Background

At present, the industry often adopts equipment with a reverse osmosis module and an Electrodeionization (EDI) module to manufacture ultrapure water (the resistivity of water is about 18M Ω · cm), but long-time operation can cause metal ion residues, insoluble carbonate, sulfate, colloid and other organic pollutants to be generated in the reverse osmosis system and the EDI module, so that the water yield is reduced, the water quality is poor, and the requirement of production water cannot be met. Generally, the above problems are solved by replacing the core module or directly rinsing the core module with acid solution circulation, but the former has high maintenance cost, and the latter has poor cleaning effect and is easy to corrode the core module.

Disclosure of Invention

In view of this, the application provides a cleaning system of ultrapure water equipment. This cleaning system has set up liquid medicine liquid storage cylinder and the pipeline of matcing with it at reverse osmosis module and EDI module respectively for reverse osmosis module can possess the pickling process, EDI module can possess the acid-base and synthesize the cleaning process, can fully clean the core module of ultrapure water equipment, thereby can guarantee that the inside cleanliness factor of core module is higher, improve the quality stability of producing water, prolong the life of core module.

The application provides a cleaning system of ultrapure water equipment in a first aspect, including ultrapure water equipment and belt cleaning device, ultrapure water equipment is including the reverse osmosis module and the electrodeionization EDI module that link to each other, belt cleaning device includes first pickling agent bin, second pickling agent bin, alkali wash storage tank, first pickling agent bin with reverse osmosis module intercommunication, second pickling agent bin, alkali wash storage tank with EDI module intercommunication;

wherein the first acid wash is used to wash the reverse osmosis module downstream; the second acid cleaning agent is used for cleaning the EDI module in a forward flow mode, and the alkaline cleaning agent is used for circularly cleaning the EDI module.

The cleaning system can be obtained by simply reforming the pipeline of the existing ultrapure water equipment, and the cleaning system has the advantages of simple equipment, low manufacturing cost, convenient operation and high cleaning efficiency.

Accordingly, a second aspect of the present application provides a method for cleaning an ultrapure water apparatus, comprising:

(1) Cleaning the reverse osmosis module by sequentially adopting a first pickling agent and water downstream; wherein the first acid washing agent comprises at least one of hydrochloric acid and phosphoric acid, and the pH value of the first acid washing agent is in the range of 1-5;

(2) Sequentially adopting a second acid cleaning agent and water to clean the EDI module downstream, and then adopting water circulation to clean the EDI module; the second acid lotion comprises organic weak acid and does not contain strong acid, and the organic weak acid comprises at least one of citric acid, acetic acid and oxalic acid; wherein the volume fraction of the weak organic acid is in the range of 1.5-3%;

sequentially cleaning the EDI module by adopting an alkaline cleaner and water circulation; the alkali washing agent comprises a mixed solution of organic alkali and inorganic strong alkali, wherein the organic alkali comprises tetramethyl ammonium hydroxide, and the inorganic strong alkali comprises sodium hydroxide and/or potassium hydroxide; wherein the volume fraction of the tetramethylammonium hydroxide is in the range of 1-3%, and the volume fraction of the sodium hydroxide is in the range of 0.3-0.8%.

Dirt particles in the reverse osmosis module are relatively large, the first pickling agent is high in concentration and strong in acidity, large-size particle dirt and impurities (calcium and magnesium impurities, indissolvable organic matters and other stubborn stains) in the reverse osmosis module can be washed away, and the washed large-particle dirt can be taken away by subsequent downstream washing, so that secondary pollution is avoided. Therefore, the reverse osmosis module can be cleaned only by adopting downstream cleaning, so that the replacement frequency of the reverse osmosis membrane can be obviously reduced, the quality of water entering the EDI module is improved, and the workload of the EDI module is reduced. And traditional circulation pickling, it is great to the washing pressure of equipment inner tube, can lead to stubborn impurity secondary under the washing to adhere to, and circulation pickling is great to the corruption of module, can harm equipment performance, detract equipment life.

The EDI module is then relatively more precise, with smaller particles of internal fouling and more metal ion impurities therein. The second acid cleaning agent with the main component of organic weak acid is adopted to flow directly to flush the EDI module, so that metal ions attached to an EDI module component can be chelated to form a metal ion chelate, the metal ion chelate can be removed by subsequent alkali cleaning agents, residual metal oxides, iron-aluminum colloids, insoluble carbonates and sulfates in the EDI module can be removed, the surface performance of an internal pipeline of the EDI module is improved, an environmental basis is provided for subsequent alkali cleaning, and the aim of thoroughly cleaning the EDI module is fulfilled. And a circulating alkali washing process is adopted subsequently, and the metal ion chelate attached to the internal pipeline can be better washed under a larger washing pressure caused by circulating washing, so that the weak acid environment in the EDI module can be better neutralized. Similarly, the circulating water washing after the concurrent acid washing and the circulating alkali washing can take away impurities washed by the acid washing and the alkali washing, so that secondary pollution is avoided.

In conclusion, according to different characteristics of the reverse osmosis module and the EDI module, the reverse osmosis module is cleaned in a downstream acid cleaning mode, and the EDI module is cleaned in a mode of organically combining a downstream acid cleaning process and a circulating alkali cleaning process, so that the cleaning effect can be considered, and the risk of damage to equipment is reduced.

Drawings

FIG. 1 is a schematic diagram of an apparatus for ultrapure water production;

FIG. 2 is a schematic view of an ultrapure water apparatus cleaning system according to an embodiment of the present application.

Description of the drawings: 11-a reverse osmosis module; 111-first pickling agent storage tank; 12-EDI module; 121-second acid lotion storage tank; 122-caustic wash reservoir.

Detailed Description

At present, the production of semiconductor devices and raw materials thereof (such as silicon carbide) requires the use of a large amount of ultrapure water (having a resistivity of 18 M.OMEGA.. Multidot.cm). Referring to fig. 1, an ultrapure water apparatus commonly used in industry generally includes a pretreatment device, a reverse osmosis module, an EDI module, and a polishing mixed bed, which are connected in sequence, wherein the pretreatment device generally includes a multistage filter, the reverse osmosis module generally includes a first-stage reverse osmosis module and a second-stage reverse osmosis module, each reverse osmosis module is provided with a Reverse Osmosis (RO) membrane and internal pipelines of each stage, the EDI module is an organic combination of electrodialysis and ion exchange, and has therein a multistage anion/cation exchange membrane, an ion exchange resin filled between the two, and internal pipelines of each stage (such as a concentrated water pipeline, an ion exchange channel, a water production pipeline, etc.), and the polishing mixed bed further improves water quality by using the ion exchange resin. In the preparation process of the ultrapure water, the ultrapure water is generally obtained by sequentially passing the pretreated water obtained by the pretreatment device through the reverse osmosis module, the EDI module and the polishing resin bed. However, the pretreated water still contains various metal ions, such as calcium ions, magnesium ions, iron ions and the like, and also contains a certain amount of organic pollutants. Therefore, after the ultra-pure water machine is used for a long time, pollutants are accumulated in the ultra-pure water machine, and the pollutants comprise metal ions, calcium and magnesium precipitates, iron-aluminum colloid and other indissolvable organic pollutants. The accumulation of the above-mentioned pollutants can cause the high-load operation of the equipment, the water yield is reduced, the water quality is reduced, and the requirements of industrial production can not be met.

The reverse osmosis module and the EDI module which are used as core components of the ultrapure water equipment determine the quality of produced water according to the cleaning degree in the modules, and the relatively large amount of dirt and relatively large stubborn stains in the reverse osmosis module can be calculated according to the operation mechanism of the ultrapure water equipment without difficulty. The EDI module is more precise, although the amount of impurities inside the EDI module is relatively small. In the traditional process, a single pickling cleaning reverse osmosis module and an EDI module are directly adopted, but impurities in the EDI module cannot be cleaned by adopting a downstream cleaning process, and equipment is corroded by adopting circulating pickling, so that the service life of the equipment is seriously influenced. It can be seen that it is difficult to efficiently and thoroughly clean ultrapure water equipment without damage and to maintain the high-load and high-quality operation of an ultrapure water machine. In order to solve the above problem, the embodiment of the present application provides a cleaning system of an ultrapure water device.

Referring to fig. 2, an embodiment of the present application provides a cleaning system for an ultrapure water device, including an ultrapure water device and a cleaning apparatus, the cleaning apparatus includes a first pickling agent storage tank 111, a second pickling agent storage tank 121, and an alkaline cleaning agent storage tank 122, the first pickling agent storage tank 111 is communicated with the reverse osmosis module 11, and the second pickling agent storage tank 121, the alkaline cleaning agent 122 storage tank are communicated with the EDI module 12.

It can be understood that a communication pipeline is arranged between each storage box and the water inlet of each module, and a valve can be arranged on the pipeline. Communication pipelines are also arranged among the modules and among all levels of structures in the modules.

In this application, reverse osmosis module 11 includes one-level reverse osmosis module and second grade reverse osmosis module, and the intaking of reverse osmosis module 11 is preliminary treatment water, and the intaking of EDI module 12 is the second grade reverse osmosis water that obtains after reverse osmosis treatment.

In this application, the belt cleaning device of above-mentioned reverse osmosis module can set up in one-level reverse osmosis module department, also can set up in second grade reverse osmosis module department, can also all set up in one-level, second grade reverse osmosis module department.

The first pickling agent is used for washing the reverse osmosis module 11 downstream; the second acid wash is used to wash the EDI module 12 downstream and the caustic wash is used to wash the EDI module 12 cyclically.

Wherein, downstream cleaning specifically means: water or drug solution wash is fed from the water inlet (I) of the reverse osmosis module 11 or EDI module 12 ₁ Or I ₂ ) Pumping with a certain flushing water pressure to make water or lotion flow along the pipe in the module and flow out of the module water outlet (O) ₁ Or O ₂ ) And is discharged into a waste liquid collecting device. The circulating cleaning specifically comprises the following steps: after the water outlet of the EDI module is closed, water or alkaline detergent is fed from the water inlet I of the EDI module ₂ Pumping with certain flushing water pressure, and closing the water inlet I of the EDI module when reaching a preset amount ₂ The water or the alkaline detergent circularly flows in the EDI module under a certain water pressure, and after a certain time, the waste liquid is discharged from the water outlet O ₂ Pumped out and discharged into a waste liquid collection device.

In some embodiments of the present application, second acid wash storage tank 121 is in communication with EDI module 12 via a first conduit, and caustic wash storage tank 122 is in communication with EDI module 12 via a second conduit.

In other embodiments of the present application, the second acid detergent storage tank 121 and the alkaline detergent storage tank 122 are in communication with the EDI module 12 through a first pipe, which is far away from the EDI module water inlet I ₂ Is branched into a first branch and a second branch, wherein the first branch is communicated with the second acid lotion storage tank 121, and the second branch is communicated with the alkaline detergent storage tank 122.

In some cases, the second acid cleaning agent and the alkaline cleaning agent can be stored in the same liquid storage tank in stages. At this time, the tank may be washed with water first when the detergent is replaced.

In some cases, other chemical storage tanks, such as a non-oxidizing sterilization lotion storage tank, may be added to the reverse osmosis module 11 and/or the EDI module 12.

Correspondingly, the embodiment of the application also provides a cleaning method of the ultrapure water device, which comprises the steps of cleaning the reverse osmosis module 11 and the EDI module 12. The order of cleaning the reverse osmosis module 11 and the EDI module 12 is not particularly limited in this application. The reverse osmosis module 11 may be cleaned first, the EDI module 12 may be cleaned first, and even the reverse osmosis module 11 and the EDI module 12 may be cleaned simultaneously.

The step of cleaning the reverse osmosis module 11 comprises: cleaning the reverse osmosis module 11 by sequentially adopting a first pickling agent and water downstream; wherein the first acid washing agent comprises at least one of hydrochloric acid and phosphoric acid, and the pH value of the first acid washing agent is in the range of 1-5. The downstream cleaning with the first pickling agent (aqueous solution of hydrochloric acid and phosphoric acid) can remove insoluble stains such as calcium carbonate, calcium sulfate and most of insoluble organic matters in the reverse osmosis module 11 (RO membrane and module internal pipeline) simply and efficiently, and the subsequent downstream straight-through cleaning can not only wash away residual acid but also perform a physical cleaning function, thereby cleaning the reverse osmosis module 11 more fully. In addition, the pH value of the first pickling agent is controlled within the range of 1-5, so that the impurities can be effectively cleaned, and the equipment can be prevented from being corroded too strongly by acidity. In addition, the concurrent pickling has less corrosion damage to equipment.

Herein, the pH of the first pickling agent may be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc., for example.

In the present application, the water for cleaning the reverse osmosis module 11 may be pre-treated water taken from an ultrapure water device or produced water from other modules in an ultrapure water device, or may even be introduced water from other places, as long as the water quality reaches the standard, the introduced water may be temporarily stored in the first pickling agent storage tank 111 or other storage devices communicating with the reverse osmosis module 11. In particular, if water temporarily stored in the first pickling agent storage tank 111 introduced elsewhere is used, it is necessary to clean the first pickling agent storage tank 111 before storing the water.

In some embodiments of the present application, the washing pressure of the first pickling agent and the washing pressure of the water are independently in the range of 0.1MPa to 0.3MPa. Preferably, the washing pressure of the first pickling agent and the washing pressure of the water are independently 0.1MPa to 0.2MPa. Illustratively, the rinse pressures of the first pickling agent and water can be independently 0.1MPa, 0.12MPa, 0.13MPa, 0.14MPa, 0.15MPa, 0.16MPa, 0.17MPa, 0.18MPa, 0.19MPa, 0.2MPa, 0.25MPa, 0.3MPa, and the like. The flushing pressure is controlled within a proper range, so that the cleaning effect can be ensured, and the risk of equipment damage can be effectively reduced.

The step of cleaning the reverse osmosis module 12 comprises: 1) Sequentially cleaning the EDI module 12 by adopting a second acid cleaning agent and water downstream, and then cleaning the EDI module by adopting water circulation; the second acid cleaning agent comprises organic weak acid and does not contain strong acid, and the organic weak acid comprises at least one of citric acid, acetic acid and oxalic acid; wherein the volume fraction of the weak organic acid is in the range of 1.5-3%. 2) Sequentially cleaning the EDI module 12 by using an alkaline cleaner and water circulation; the alkaline cleaning agent comprises a mixed solution of organic alkali and inorganic strong base, wherein the organic alkali comprises tetramethyl ammonium hydroxide, and the inorganic strong base comprises sodium hydroxide and/or potassium hydroxide; wherein, the volume fraction of the tetramethyl ammonium hydroxide is in the range of 1-3%, and the volume percentage of the sodium hydroxide is in the range of 0.3-0.8%.

The second acid cleaning agent containing organic weak acids (citric acid, oxalic acid and phosphoric acid) can be used as a chelating agent to form a chelate (partial chelate sediment and partial soluble chelate) with metal ions attached to the pipeline in the EDI module 12 and an ion exchange membrane, can remove metal oxides, iron-aluminum colloid, the chelate sediment and indissolvable substances (magnesium carbonate, calcium sulfate and the like) of calcium and magnesium ions to a certain extent, and can provide a proper weak acid environment to lay a foundation for subsequent alkali cleaning. In the present application, the second acid cleaning agent is not limited to the one containing a strong acid in the absolute sense of being completely ionized in water, such as hydrochloric acid, sulfuric acid, perchloric acid, and the like, and a medium strong acid in the strict sense, such as phosphoric acid, may be regarded as the "strong acid" described above. The structure of the EDI module is more precise, and the second acid cleaning agent does not contain the strong acid, so that the cleaning effect can be effectively improved, and the corrosion of equipment can be avoided. In addition, downstream cleaning can also significantly reduce the risk of acid corrosion to the EDI module 12, and subsequent downstream and recycle water washes can remove a portion of the second acid wash in the pipeline while more completely carrying away the solid impurities.

In the step 2), the alkali cleaning agent is a mixed solution obtained by mixing an organic alkali (tetramethylammonium hydroxide) and a strong base (potassium hydroxide and/or sodium hydroxide) in a certain proportion, and the two alkalis are matched with each other in a certain concentration to fully precipitate a soluble chelate formed in the acid cleaning process. In addition, the appropriate concentration ratio of the alkali washing agent and the alkaline washing agent can improve the alkali washing effect, is favorable for saving cost, and can also avoid the damage of the over-strong alkalinity to equipment. On the other hand, the reaction time of the alkaline detergent and the dirt is relatively long, and the contact time of the alkaline detergent and the internal pipeline of the module and the cleaning pressure need to be increased in a circulating cleaning mode. In addition, the alkali washing agent is a mixture of inorganic strong base and organic base, and the two agents can be further ensured to be fully dissolved mutually by adopting circulating washing, so that the combined action of the two agents can be fully exerted, and the metal ion chelate attached to the inner wall of the pipeline can be more fully precipitated and washed away. Moreover, before the alkaline washing process is started, the inner wall of the pipeline is in a weak acid environment, and irreversible damage to equipment cannot be caused by adopting circulating alkaline washing. Finally, the water is washed by combining with circulating water, so that the cleanliness of the interior of the pipeline can be fully ensured, and the aim of thoroughly cleaning water equipment is fulfilled.

The cleaning method adopts different process schemes to clean according to the characteristics of different modules of the ultrapure water equipment, has the advantages of simple process, high cleaning efficiency, low cost, less damage to the equipment and good cleaning effect, and can obviously reduce the cleaning frequency of the ultrapure water machine, maintain the high water purifying capacity of the reverse osmosis module 11 and the EDI module 12 for a long time after cleaning, reduce the workload of a subsequent polishing mixed bed, reduce the replacement frequency of ion exchange resin in the polishing mixed bed and reduce the cost, so that the ultrapure water machine can run with high load and high quality for a long time, and can prolong the service life of the ultrapure water.

In this application, similarly, the water that washs EDI module 12 can be the second grade reverse osmosis water in the ultrapure water equipment, also can the water that quality of water up to standard that other places introduced. The water introduced elsewhere may be temporarily stored in the second pickling tank 121 and/or the alkaline detergent storage tank 122, or may be stored in another storage device which is additionally provided and may be communicated with the EDI module 12, and it should be noted that the second pickling tank 121 and/or the alkaline detergent storage tank 122 need to be cleaned before the water is stored.

In the present application, the volume fraction of weak organic acids may be, for example, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, etc. Preferably, in some embodiments of the present application, the volume fraction of the weak acid is in a range of 1.5% to 2%, at this time, the removal of impurities inside the EDI module is facilitated, and metal ions attached inside the EDI module can be sufficiently chelated, so that the risk that the second acid cleaning agent corrodes the equipment can be further reduced while the cleaning effect is ensured to be good, thereby facilitating the extension of the service life of the ultrapure water equipment.

In some embodiments of the present application, the second acid washing agent is citric acid. The citric acid has a better chelating effect on metal ions in the EDI module 12, and can better remove carbonate dirt, calcium sulfate, metal oxides and iron-aluminum colloid attached to the pipe inside the EDI module 12.

In some embodiments of the present application, after the second acid cleaning agent and the water circulation cleaning the EDI module, that is, before the EDI module is cleaned by using the alkali cleaning agent, the pH of the droplets on the surface of the pipeline is maintained in a range of 2 to 5, which is more favorable for the subsequent alkali cleaning process.

In the present application, for example, the mass percentage of the tetramethylammonium hydroxide in the alkali washing agent may be 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3%, and the like; the alkali in the alkali cleaning agent may be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, or the like, in mass%.

In some embodiments of the present application, it is preferable that the percentage by mass of the tetramethylammonium hydroxide in the alkali washing agent is in a range of 1% to 2%.

In some embodiments of the present application, preferably, the mass percentage of the strong base in the alkaline detergent is in a range of 0.4% to 0.7%. In the present application, the pH of the alkaline detergent is not generally specifically limited. Illustratively, the pH of the alkaline wash may be in the range of 8-11. Illustratively, the pH of the alkaline detergent may be 8, 9, 10, 11, or the like.

The specific operation steps of forward flow cleaning and recycle cleaning are described below in conjunction with fig. 2, taking the cleaning of EDI module 12 as an example: (a) co-current acid wash EDI module 12: firstly, closing a valve C between the reverse osmosis module and the EDI module, opening a valve E of a second acid lotion storage tank, a valve D of a water inlet of the EDI module and a valve G at a water outlet of the EDI module so as to enable the second acid lotion to enter the EDI module 12 along a pipeline and flush an anion/cation exchange membrane and an internal pipeline inside the EDI module downstream, and flushing the anion/cation exchange membrane and the internal pipeline from an outlet O of the EDI module ₂ And flows out into a waste liquid collecting device. (b) downstream water washing the EDI module 12: then, the valve C is opened to enable the secondary reverse osmosis water (other water with the water quality reaching the standard can be taken) to flow into the EDI module 12, so that the water enters the EDI module 12 along the pipeline and flows to wash the anion/cation exchange membrane and the internal pipeline in the EDI module, and the water flows out of an outlet O of the EDI module ₂ And the water flows out and is discharged into a waste liquid collecting device, and the valve C is closed when the flushing water quantity reaches the preset water quantity. (c) circulating water to wash the EDI module 12: close valve G to open valve C for second grade reverse osmosis water gets into and stores in EDI module 12, closes valve D and C after reaching the preset water yield, opens the circulation mode, so that second grade reverse osmosis water carries out the circulation along EDI module 12's inside pipeline and washs, washs after the certain period, opens valve G, discharges the waste liquid into waste liquid collection device. After the cleaning is finished, operating an ultrapure water device, detecting the operation parameters of the device and the water quality of each water consumption point, and judging that the cleaning effect reaches the standard if the resistivity of the final produced water is more than or equal to 18M omega cm. If the final produced water does not reach the standard, a new round of cleaning is startedWashing until the cleaning effect reaches the standard.

In other embodiments, either concurrent or cyclic cleaning with water, the second acid wash storage tank may be cleaned with water prior to entering EDI module 12 for cleaning.

Similarly, the specific operation methods of the forward flow cleaning of the reverse osmosis module 11 and the alkaline cleaning process of the EDI module 12 can be finely adjusted by referring to the forward flow cleaning and the circulation cleaning processes, which are not described herein again. It is understood that the water for cleaning the reverse osmosis module 11 may be pre-treated water, or may be other water meeting the water quality requirement.

In some embodiments of the present application, the above steps, which are performed by water circulation washing and/or concurrent washing, may be repeated several times. In general, it can be repeated 2 times.

In some embodiments of the present application, when cleaning the EDI module 12, the flushing pressure of the second acid cleaning agent, the alkaline cleaning agent, and each water in steps 1) -2) is independently in a range of 0.1MPa to 0.3MPa. Preferably, the flushing pressure of the second acid lotion, the alkali lotion and each water is independently in the range of 0.2MPa to 0.25 MPa. Illustratively, the rinsing pressures of the second acid rinse, the caustic rinse, and each of the waters can be independently 0.1MPa, 0.15MPa, 0.2MPa, 0.21MPa, 0.22MPa, 0.23MPa, 0.24MPa, 0.25MPa, 0.3MPa, or the like. The flushing pressure is controlled within the range, so that the cleaning effect can be ensured, and the risk of equipment damage can be effectively reduced.

In some embodiments of the present application, when cleaning the EDI module, after cleaning with the alkaline detergent and the water circulation, the method further includes an optional step (3): the EDI module 12 is flushed in sequence with a non-oxidizing sterilant wash and water circulation. In some embodiments, the primary components of the non-oxidative sterilant can be chlorophenols and anionic polyacrylamide. The adoption of the cyclic cleaning of the non-oxidizing sterilizing agent washing liquid can remove microorganisms in the EDI module 12, thereby being beneficial to the long-time size running of the ultrapure water equipment and further prolonging the cleaning period of the ultrapure water equipment to one month.

In some embodiments of the present application, the non-oxidizing sterilant wash includes a non-oxidizing sterilant in a range of 5% to 10% by weight. For example, the non-oxidizing sterilant in the non-oxidizing sterilant wash may be 5%, 6%, 7%, 8%, 9%, 10%, or the like, by mass.

In this application, non-oxidizing sterilant lotion can be stored in second acid lotion storage tank, also can store in alkaline lotion storage tank, can even store in the non-oxidizing sterilization lotion storage tank that sets up separately. It should be noted that if the non-oxidizing sterilant solution is stored in the second acid solution storage tank or the alkaline solution storage tank, the storage tank needs to be washed with water before the chemical solution is injected.

In some embodiments of the present application, when the EDI module is cleaned, in the step 1), the step 2) and the optional step (3), the cleaning time of each cycle is independently 15min to 30min. Preferably, the time for each cycle of cleaning is independently 20min to 30min. Sufficient circulation cleaning time can make metal ion chelate fully react with the alkaline detergent, in addition, sufficient circulation washing time is more favorable to taking away the impurity residue in EDI module 12, improves final clean effect.

The technical scheme of the application is described by combining the embodiment.

Example 1

(1) And (3) preparing a hydrochloric acid solution in the first pickling agent storage tank to enable the pH value of the first acid agent to be about 2, carrying out concurrent cleaning on the reverse osmosis module at a flushing pressure of 0.1MPa, and discharging the waste liquid into a waste liquid collecting device. Then 500L of pretreatment water is taken, the water is directly fed through the reverse osmosis module at the washing pressure of 0.2MPa, and the water washing process is repeated twice.

(2) 200L of 1.5% citric acid is added into the second acid lotion storage tank, the EDI module is cleaned with a flushing pressure of 0.1MPa, and the waste liquid is discharged into a waste liquid collecting device. Then 200L of secondary reverse osmosis water is taken, and the washing is carried out directly and downstream at the washing pressure of 0.2MPa, and the water washing process is repeated twice.

(3) And cleaning the EDI module by using 200L of secondary reverse osmosis water in a circulating manner, wherein the washing pressure is 0.25MPa, and the water washing process is repeated twice.

(4) 200L of alkaline cleaning agent is proportioned in the alkaline cleaning agent storage tank, wherein the alkaline cleaning agent is 0.5% of sodium hydroxide and 2% of tetramethyl ammonium hydroxide, the EDI module is cleaned circularly under the flushing pressure of 0.1MPa, and the waste liquid is discharged into a waste liquid collecting device. And cleaning the EDI module by using 200L of secondary reverse osmosis water in a circulating manner, wherein the washing pressure is 0.2MPa, and the water washing process is repeated twice.

Example 2

The only differences from example 1 are: further comprising the step (5): 200L of 5% non-oxidizing sterilant (mainly composed of chlorophenols and anionic polyacrylamide) solution was mixed in a non-oxidizing sterilant solution storage tank, and the mixture was washed cyclically at a washing pressure of 0.1MPa, and the waste solution was discharged into a waste solution collecting device. And then cleaning the EDI module by adopting 200L of secondary reverse osmosis water in a circulating way, wherein the flushing pressure is 0.2MPa, and the water flushing process is repeated twice.

Example 3

The only differences from example 2 are: in the step (1), the pH value of the first pickling agent is 5; in the step (2), the second acid lotion is 1.5% of citric acid; in the step (4), the alkali washing agent is 0.3% of sodium hydroxide and 2% of tetramethyl ammonium hydroxide; in the step (5), 3% of non-oxidative sterilizing agent.

Example 4

The only differences from example 2 are: in the step (1), the pH value of the first pickling agent is 1; in the step (2), the second acid lotion is 2% citric acid; in the step (4), the alkali washing agent is 0.8% of sodium hydroxide and 2% of tetramethyl ammonium hydroxide; in the step (5), 7 percent of non-oxidizing sterilizing agent is added.

Example 5

The only differences from example 2 are: in the step (2), the second acid lotion is 3% citric acid.

Example 6

The only differences from example 2 are: in the step (4), the alkali wash is 0.5% of sodium hydroxide and 1% of tetramethylammonium hydroxide.

Example 7

The only differences from example 2 are: in the step (4), the alkali washing agent is 0.5% of sodium hydroxide and 3% of tetramethyl ammonium hydroxide.

Example 8

The only differences from embodiment 1 are: in the step (1), the flushing pressure of the first pickling agent is 0.05MPa; in the step (2), the flushing pressure of the second acid cleaning agent is 0.05MPa; in the step (4), the washing pressure of the alkali washing agent is 0.05MPa; in the step (5), the flushing pressure of the non-oxidizing sterilant washing solution is 0.05MPa.

Example 9

The only differences from example 2 are: in the steps (1) to (5), in each forward flow cleaning or circulating cleaning process, all cleaning pressures are 0.3MPa.

Example 10

The only differences from example 1 are: in the step (2), the second acid cleaning agent is 1.5% oxalic acid.

In order to highlight the advantageous effects of the examples of the present application, the following comparative examples were provided.

Comparative example 1

(1) 500L of 0.5% hydrochloric acid is prepared in a first pickling agent storage tank, the reverse osmosis module is cleaned with a flushing pressure of 0.1MPa downstream, and waste liquid is discharged into a waste liquid collecting device. Then 500L of pretreatment water is taken, the water is directly fed through the reverse osmosis module at the washing pressure of 0.2MPa, and the water washing process is repeated twice.

(2) 200L of mixed acid liquor of 1.5% citric acid and 0.5% hydrochloric acid is prepared in a second acid lotion storage tank, the EDI module is cleaned in a forward flow mode under the flushing pressure of 0.1MPa, and waste liquid is discharged into a waste liquid collecting device. Then 200L of secondary reverse osmosis water is taken, washing is carried out directly and downstream at the washing pressure of 0.2MPa, and the water washing process is repeated twice.

(3) And cleaning the EDI module by adopting 200L of secondary reverse osmosis water circulation, wherein the flushing pressure is 0.25MPa, and the water flushing process is repeated twice.

(5) 200L of 5% non-oxidizing sterilant (mainly composed of chlorophenols and anionic polyacrylamide) solution was mixed in a non-oxidizing sterilant solution storage tank, and the mixture was washed cyclically at a washing pressure of 0.1MPa, and the waste solution was discharged into a waste solution collecting device. And then cleaning the EDI module by adopting 200L secondary reverse osmosis water in a circulating way, wherein the washing pressure is 0.2MPa, and the water washing process is repeated twice.

Comparative example 2

The only differences from comparative example 1 are: step (2): 200L of hydrochloric acid with the pH value of 2 is prepared in the second acid lotion storage tank, the EDI module is circularly cleaned under the flushing pressure of 0.1MPa, and the waste liquid is discharged into the waste liquid collecting device. Then 200L of secondary reverse osmosis water is taken, and the washing is carried out directly and downstream at the washing pressure of 0.2MPa, and the water washing process is repeated twice.

Comparative example 3

The only differences from example 2 are: in the step (1), the pH of the first pickling agent is 1; in the step (2), the second acid lotion is 0.1% of citric acid.

Comparative example 4

The only differences from example 2 are: in the step (1), the pH of the first pickling agent is 1; in the step (2), the second acid lotion is 3.5% of citric acid.

Comparative example 5

The only differences from example 2 are: in the step (4), the alkali wash is 0.5% ammonia water and 2% tetramethyl ammonium hydroxide.

Comparative example 6

The only differences from example 2 are: in the step (4), the alkali washing agent is 1% of sodium hydroxide and 0.5% of tetramethylammonium hydroxide.

Comparative example 7

The only differences from comparative example 1 are: in the step (1), the pH value of the first pickling agent is 6.

Before the ultrapure water equipment is cleaned according to each embodiment and each proportion step, the performance parameters and the water point water quality off-line detection parameters of the ultrapure water equipment are summarized in table 1, and the water quality standards which the produced water of the ultrapure water equipment should reach are also summarized in table 1.

The reverse osmosis module and the EDI module of the ultrapure water apparatus to be cleaned were cleaned according to the cleaning steps of the above examples and comparative examples. And detecting all parameters of the cleaned ultrapure water equipment and the quality of the produced water in all process nodes.

And (3) resistivity testing: the resistance condition of the water quality can be accurately tested by adopting an online resistance meter for testing, and the resistance of the water quality reflects the content of impurities such as metal ions in water; on the other hand, the more obvious reduction of the resistance after cleaning can also reflect the condition that the cleaning module is corroded and damaged.

Detecting the impurity content of the particles: adopting Japanese sound-handling KS42-AF equipment for off-line detection, taking hundred-grade clean areas as sampling points, and adopting a soluble Polytetrafluoroethylene (PFA) clean bottle for sampling. The results may reflect the water particle impurity content.

The results are summarized in table 2.

It should be noted that the higher the degree of cleaning inside the ultrapure water apparatus, the lower the water inlet pressure at the water inlet of the apparatus. In addition, after the internal pipeline of the ultrapure water device is unblocked, the water yield of the ultrapure water device can reach the maximum value (the actual water yield of the ultrapure water device with the rated water yield of 1T/H can reach 1.1T/H), and the resistivity of the finally obtained water can reach 18M omega cm. On the other hand, the smaller the concentrated water discharge amount of the EDI module is, the higher the cleaning degree of the interior of the EDI module is, the water quality stabilization time of the water produced after the ultrapure water equipment is cleaned is generally controlled within 15h, and the longer the concentrated water discharge amount is, the more the chemical liquid medicine is left in the equipment, so that the equipment is corroded after the ultrapure water is cleaned for many times, and the performance of the EDI module is reduced and the service life of the EDI module is damaged.

TABLE 1 parameter summarization of water quality standards before and after cleaning of ultrapure water equipment

TABLE 2 parameter summary after cleaning by ultrapure water equipment

In other words, even if the quality of the water produced by the cleaned device reaches the standard, the water quality may be unstable (peculiar smell occurs, etc.) or the device operation may not be stable, and the water can be produced continuously and stably after the water is buffered for a certain time. Therefore, the normal operation is recovered within 15h indicated in the remark column, which means that the water can be stably supplied within 15h after the ultrapure water device is cleaned according to the detection standard after the ultrapure water device is cleaned. Similarly, the stability of water quality within 30 hours noted in the above respective proportions means that no peculiar smell water can be stably and continuously produced after the equipment is cleaned and operated for 30 hours, but the water quality of the produced water still can not reach the standard of ultrapure water.

As can be seen from the data in table 1, after the pure water equipment is cleaned according to the steps of the embodiments, the water inlet pressure of the total water inlet of the equipment is obviously lower than that of the comparative example, and the water yield is obviously higher than that of the comparative example. Moreover, the resistivity of the comparative produced water does not meet the ultrapure water standard. Furthermore, the concentrate production of the EDI module is lower compared to the comparative example. The above data fully illustrate that the cleaning method provided by the application has better cleaning effect.

The foregoing is illustrative of the present application and it will be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles of the invention, and that such changes and modifications are to be considered as within the scope of the invention.

Claims

1. The cleaning system of the ultrapure water equipment comprises the ultrapure water equipment and a cleaning device, wherein the ultrapure water equipment comprises a reverse osmosis module and an electrodeionization EDI module which are connected, and is characterized in that the cleaning device comprises a first pickling agent storage tank, a second pickling agent storage tank and an alkaline washing agent storage tank, wherein the first pickling agent storage tank is communicated with the reverse osmosis module, and the second pickling agent storage tank and the alkaline washing agent storage tank are communicated with the EDI module;

wherein the first acid wash is used to wash the reverse osmosis module downstream; the second acid washing agent is used for washing the EDI module in a concurrent flow mode, and the alkaline washing agent is used for circularly washing the EDI module.

2. The cleaning system of claim 1, wherein the second acid wash storage tank is in communication with the EDI module through a first conduit and the alkaline wash storage tank is in communication with the EDI module through a second conduit.

3. A method for cleaning an ultrapure water device, comprising:

(2) Sequentially cleaning the EDI module by adopting a second acid cleaning agent and water downstream, and then cleaning the EDI module by adopting water circulation; the second acid lotion comprises organic weak acid and does not contain strong acid, and the organic weak acid comprises at least one of citric acid, acetic acid and oxalic acid; wherein the volume fraction of the weak organic acid is in the range of 1.5-3%;

sequentially cleaning the EDI module by adopting an alkaline cleaner and water circulation; the alkali washing agent comprises a mixed solution of organic alkali and inorganic strong alkali, wherein the organic alkali comprises tetramethyl ammonium hydroxide, and the inorganic strong alkali comprises sodium hydroxide and/or potassium hydroxide; wherein the volume fraction of the tetramethylammonium hydroxide is in the range of 1-3%; the volume percentage of the sodium hydroxide and/or the potassium hydroxide is in the range of 0.3 to 0.8 percent.

4. The cleaning method according to claim 3, wherein the volume percentage of the weak organic acid is in a range of 1.5% to 2%.

5. The cleaning method according to claim 3 or 4, wherein the weak organic acid is citric acid.

6. The cleaning method according to claim 3, wherein the volume fraction of the tetramethylammonium hydroxide is in the range of 1% to 2%.

7. The cleaning method according to claim 3, wherein the pH of the droplets on the surface of the internal pipe of the EDI module is in the range of 2-5 before the EDI module is cleaned with the alkaline detergent.

8. The cleaning method according to claim 3, wherein the rinsing pressures of the first acid washing agent, the second acid washing agent, the alkali washing agent, and each water are independently in the range of 0.1MPa to 0.3MPa.

9. The cleaning method according to claim 3, wherein the time of the cyclic cleaning is independently 15min to 30min.

10. The cleaning method according to claim 3, further comprising (3): and sequentially adopting a non-oxidizing sterilizing agent washing liquid and water to circularly wash the EDI module.