In today's water treatment field, EDI is a brand-new precision desalination technology. Its main feature is that the product process structure and working principle fully and effectively integrate the working characteristics of ion exchange and electrodialysis. The so-called ion exchange is the equal charge reaction between the ions in the water and the functional groups on the ion exchange resin. It uses the active groups on the anion and cation exchange resins to selectively adsorb anions and cations in water. During the contact between water and the ion exchange resin, the hydroxide ions (OH-) in the anion exchange resin are dissolved together The anions in the water (such as CI-, etc.) are exchanged, and the hydrogen ions (H+) in the cation exchange resin are exchanged with the cations (such as Na+, etc.) dissolved in the water. So that the anions and cations dissolved in the water are removed, achieving the purpose of purification.
Before the EDI system is put into operation, the correct system operation management is the key to ensuring the long-term high-performance and stable operation of the system. It includes the detection and adjustment of the water quality before the system is put into operation, so that it can be included in the standard range. This should not only be given in the design Full consideration, and must be implemented in the installation and commissioning, operation training and future operation management. Operation records must be kept and data standardized, so that the actual performance of the system can be grasped in time, and corrective measures should be taken immediately if necessary. When system performance assurance requirements are put forward, complete and accurate records must also be provided.
1. Things to check before starting
(1) Whether all the water inlet and outlet ports of the module block are well connected with the system pipeline.
(2) Whether the power and water pretreatment system can operate continuously.
(3) Whether the pipeline has been flushed.
(4) Whether on-site electrical wiring and grounding have been tested.
(5) Whether the pump and rectifier are both in the "off" state.
2. The basic steps of startup
(1) Fill the system with water that meets the water inlet conditions.
(2) Start the EDI circulating pump, adjust the fresh water inlet and outlet valves, so that the module's water output and pressure are within the specified value range.
(3) Adjust the concentrated water inlet valve to make the inlet water flow, concentrated water discharge flow, polar water discharge flow and concentrated water inlet and outlet pressures within the specified value range.
(4) Start the rectifier to make the module run under the stabilized voltage state, and slowly adjust the current knob clockwise to the specified value. For the EDI system to work effectively, the conductivity of the concentrated water should be controlled between 10-250uS/cm. Through 500uS/cm, when necessary, turn on the salt pump and add salt solution to the concentrated water pipeline to improve the conductivity.
3. Shutdown steps
(1) Turn the hour hand of the current knob to 0 and turn off the rectifier.
(2) Press the EDI cycle stop button.
(3) Close the main water inlet valve.
4. Safety matters
(1) The EDI system runs under high voltage, and the rectifier power supply must be cut off before any maintenance.
(2) There are gases such as CO2, H2, and O2 in the water discharged from the electrode. The concentration is generally low and will not cause explosion and irritation problems. However, in order to ensure safety, it is recommended to be taken outdoors.
(3) The module itself and all conductive parts have a common ground, but do not touch it during operation.