Cleaning conditions:

When the temperature and flow rate are unchanged, the differential pressure of produced water increases by 50%, or when the temperature and flow rate are unchanged, the differential pressure of concentrated effluent increases by 50%, or when the temperature, flow rate or inlet conductance are unchanged, the quality of produced water decreases, or when the temperature and conductance of concentrated water are unchanged, the resistance of the assembly increases by 25%.

Selection of cleaning scheme

Cleaning scheme (1): use acid solution to clean the concentrated water circulation system.

Cleaning scheme (2): use acid solution to simultaneously pickle the thick water room and the fresh water chamber.

The cleaning scheme is suitable for the non-organic contamination of ion exchange resins in freshwater chambers due to the excessive content of Fe or Mn in the influent water or the occasional high TDS in the influent water of EDI modules. In addition, it is also easy to scale in concentrated water chambers under these conditions. Therefore, it is recommended to clean all the fresh water chambers and dense water chambers in the EDI module.

Cleaning scheme (3): use alkaline solution to wash the thick water room and fresh water room at the same time.

When the organic content in the influent exceeds the design standard, the ion exchange resin in the dilute chamber may be contaminated by organic matter. The high pH alkali solution passes through the freshwater chamber, and the organic pollutants in the ion exchange resin can be cleaned out. The same solution through the concentrated water circulation system can remove the contamination caused by any organic matter in the concentrated water chamber.

Cleaning scheme (4): acid solution pickling concentrated water chamber, fresh water chamber, and then alkaline solution at the same time alkaline washing concentrated water chamber, fresh water chamber.

When conditions are favorable for the survival of microorganisms, some bacteria and algae will be produced in the EDI module, resulting in microbial contamination. At the same time, if there is inorganic contamination or fouling caused by the component, the component needs to be acid-washed.

Cleaning contaminated EDI components is not as good as cleaning regular EDI components before that. It is suggested that preventive cleaning should be carried out periodically according to the contamination situation of the components.

Cleaning scheme (5): Sodium hypochlorite solution is used to clean the components, which is a more effective cleaning scheme for the components with serious biological pollution.

Cleaning program (6): For the inorganic pollution or fouling pollution and biological pollution at the same time, the acid solution pickling chamber, fresh water chamber, and then the use of sodium hypochlorite solution to clean the components.

Explain:

The entire cleaning process of the EDI plant takes about several hours.

After cleaning, EDI components must be regenerated (except cleaning scheme 1). The regeneration time is about 16.

If the EDI device shutdown time exceeds three days after cleaning, maintenance must be carried out in accordance with the requirements of long shutdown.

Chemical cleaning agent requirements

NaCI for analytical purity (299.8%), ACS level, configured to 5%NaCI

NaOH particle analysis, ACS grade or 40% diaphragm caustic solution, configured as 1%NaOH solution.

Sodium hypochlorite is 0.5% sodium hypochlorite for analytical purity and ACS grade.

HCI is ACS level and configured to 2%HCI.

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KHN water treatment equipments Co., Ltd.                             www.khnwatertreatment.com