Methods for adjusting flow rate and voltage in electronic-grade high-purity water equipment

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This post was last edited by hesonchang214 on 2020-3-7 at 10:23. In order to ensure that the water quality meets the required standards while the industrial pure water equipment is in operation, so that all ionic substances in the raw water are removed and the equipment can remain in a balanced state with its operating conditions remaining normal, it is necessary to properly adjust the inlet flow rate, concentrate flow rate, and voltage of the EDI equipment. So, how are the flow rate and voltage adjustment methods for industrial pure water equipment operated? 　　Adjustment of the inlet flow rate for industrial pure water equipment As the inlet flow rate increases, the operating pressure of the modules also rises; if this exceeds the processing capabilities of the EDI system, the quality of the output water will deteriorate significantly. Therefore, when the conductivity of the incoming water is relatively high, it is necessary to adjust the flow rate of the incoming water appropriately. When the conductivity of the feed water is relatively low, it is also possible to increase the flow rate of the feed water within the permissible pressure limits of the EDI system, thereby improving the water production efficiency. 　　Adjustment of the concentrated stream flow rate in industrial pure water equipment The variation in the concentrated stream flow rate is another factor that affects the balance of the system, particularly as it has a direct impact on the current within the system. The flow rate of the concentrated solution also has a certain impact on the removal of the weakly charged ion Si. The solubility of Si in water at 25°C with a pH of 6–8 is 120 mg/L. Therefore, once the concentration ratio of the incoming water reaches a certain level, Si becomes saturated in the concentrated solution, preventing further silicon removal; this is also one of the conditions that determine the lower limit for the flow rate of the concentrated water. 　　Adjustment of the voltage in industrial pure water equipment
If the voltage decreases or the total ion level in the incoming water rises, the resin within the system will exchange ions more frequently. Consequently, the operating range shifts toward the effluent side until a new equilibrium is reached or breakthrough occurs. During this process, the conductivity of the effluent undergoes certain changes; the most noticeable effect is an increase in weakly charged ions in the effluent. If the voltage increases or the amount of ions in the incoming water decreases, the operating range of the system shifts toward the incoming water side, resulting in improved water quality at the outlet and a reduced level of weak electrical ions. Therefore, the equilibrium state of the system can be determined by changes in the quality of the effluent water and the amount of weakly charged ions that leak out, and it can also be explained through shifts in the operating range.