Handling of tripping caused by low flow rate of brine feed to the ion-exchange membrane cell in chlorine production plants
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The chlorine production ion-exchange membrane cells are operating at full capacity. There is an interlock shutdown mechanism that triggers when the flow rate of the brine entering the cells falls below a certain level for 90 seconds; this usually happens when there is saltwater circulation but the flow rate of the brine entering the cells is low. In special circumstances, however, the saltwater circulation pumps or the brine pumps may also stop working (meaning no brine enters the cells anymore). It might still be possible to restart these pumps. At high electric densities, is it acceptable to wait for the 90-second interlock shutdown period? Could the absence of brine lead to an explosion due to the cells drying out over those 90 seconds? Another question: at what level of traffic do the experts set the threshold for kicking off the service after 90 seconds? What is the basis for this setting? We have set it at 8 cubic feet per hour.
For the basis, you can consult the Chlorine Engineering Technology Service Department by phone directly. It is generally not a big problem to switch to another pump for supplying saline within 90 seconds. If that doesn’t work, it’s safer to let it trip via interlock.
The minimum flow rate is a variable that increases automatically based on the current density (according to the formula provided by the manufacturer); it is not fixed. With complete flow interruption, there’s no need to worry about dry burning, even if the pump can’t be revived in time. There is also a interlock shutdown for excessively high slot voltage.
The brine in the high-level brine tank can also be used as a temporary emergency solution; in addition, the electrolyzer is equipped with an interlock that activates when the brine flow rate is low
Thank you very much for your guidance. Are you also using cells in chlorine engineering? Have you ever encountered a situation where the saltwater flow was completely cut off? Also, what is the formula for setting the minimum flow rate for saltwater and alkali? We haven’t heard anything about it from the chlorine engineering team.
Is there no brine high-level tank? The sump also serves as a buffer; generally, setting the liquid level alarm at a value 5 points lower than the normal level allows for early detection of problems with the pump. For example, if the normal level is 85%, setting the alarm at 80% enables one to calculate how long the available volume will last, which can serve as a basis for emergency response. Generally, pump replacement is needed urgently. Unless the high-level tank shows a false level due to crystallization.
For saline, we use 1.894 * current; the normal flow rate is 2 * current (with slight adjustments based on the concentration of the brackish water). Each unit cell has different coefficients as well. Set it at 90% of the normal flow rate. Most of the chlorine processes do not have high-level tanks. The design section at the back is also available now.
First of all, thank you for your reply. What I’m referring to is not the flow rates of saltwater and alkali during normal production, but rather the flow rates at which an alarm should be triggered. That is, the system will trigger an alarm if the flow rate of the secondary saltwater falls below a certain level after 90 seconds, and the same applies if the flow rate of alkali falls below its set level after 300 seconds. What are the typical values you set for these minimum flow rates of saltwater and alkali? What is the basis for this setting? Our chlorine plant electrolyzers currently do not have saltwater and alkali sumps.
It’s asking how this low interlock value is set, and what the basis for setting it is Is there a formula for the calculation? And what determines the low interlock value for alkalis?
Our chlorine engineering cells do not have high-level salt tanks or alkali storage tanks; instead, pumps supply the liquid directly into the cells.
0.9 * the normal saline flow rate at this current value is the 90S interlock value. Provided by Chlorine Engineering; the basis for this estimate is their empirical values (saltwater concentration below a certain value)