A minor issue with the battery cell
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This post was last edited by sunjl1981 on 2013-1-6 at 23:38. In the initial period after the electrolyzer is started up, the cell voltage is slightly lower than it was before shutdown; however, as operating time increases, the rate of increase in cell voltage is fast, and it rises every day. I would like to ask my colleagues: what causes the slot pressure to keep rising? ? # ， ， &
This post was last edited by Yinozhang on 2012-4-27 at 16:46. Are you using a diaphragm cell or an ion-exchange membrane cell? In fact, the drop in cell voltage is due, on the one hand, to a passivation film that forms on the anode during the electrolysis process; after shutdown, the reverse potential causes this passivation film to dissolve, leading to a decrease in the anode potential. On the other hand, after shutdown, the electrolyte circulates for a period of time, and during this circulation some of the impurities deposited on the membrane are washed away, which also results in a decrease in the membrane potential. These two factors combined cause the cell voltage to drop. However, as more impurities accumulate on the membrane over time, the voltage rises again.
As metal deposits continue to accumulate on the surface of the membrane, this causes the cell voltage to rise. After the system is shut down and cleaned, the deposits on the membrane surface are removed; however, they start accumulating again once the system is restarted.
If it’s a diaphragm electrolyzer, then there’s an issue with the quality of your brine. Under normal circumstances, the sediment on the membrane decreases during shutdown, which reduces the membrane pressure drop. After the system is restarted, poor quality of the brine leads to an increase in the membrane voltage, thereby affecting the overall voltage.
First, I would like to ask whether you are using diaphragm electrolyzers or ion-exchange membrane electrolyzers. If nothing goes wrong, I assume you are using ion-exchange membrane electrolyzers. Regarding the issue of the cell voltage continuing to rise, there are mainly the following possible reasons: 1. The DCS display may be incorrect; in reality, the voltage does not rise, so this should be ruled out first. 2. Changes in the control parameters of the process can also be ruled out as a cause. 3. The most likely reason is that during shutdown, the saltwater circulation removes some impurities from the membrane, which results in a temporary decrease in current when the system is restarted. Additionally, the coating on the electrode plates might peel off due to insufficient protection against polarization currents during shutdown; as a result, the current rises quickly, but it will stabilize after operating for some time. I suggest that you continue to monitor the situation and rule out any process-related causes
We are ion-exchange membrane electrolyzers; these electrolyzers are old forced-circulation bipolar electrolyzers from Beihua Machinery. As everyone has said, \"Because metal deposits keep accumulating on the surface of the membrane, this causes the cell voltage to rise. After the system is shut down and cleaned, the deposits on the membrane surface are removed, but they start to accumulate again once the system is restarted.\" ”In this situation, the slot voltage should stabilize once it reaches a certain value, but in our case it keeps rising continuously. When we restart the machine after parking it in our unipolar slot, the voltage in the slot is a bit low at first, but it gradually rises to its level before parking over the course of two days and stays stable; moreover, it remains very stable during operation, with no increase of even 0.1V in a whole year. Moreover, we share one brine system for the two sets, so I don’t think it’s a brine issue.
What is the change in tank temperature as the tank pressure increases? Does the tank temperature also continue to rise as the tank pressure increases?
This post was last edited by Yinozhang on 2012-4-27 at 16:47. I disagree with what was said on the third floor; stopping frequently to clean the tank is not a sustainable solution; the root cause should be identified.
Simply put, the resistance increases and the voltage rises
We keep the temperature of our electrolytic cells at around 87 degrees to ensure stable operation
After stopping the operation for a while before resuming it, the voltage may drop. This is because during the shutdown period, saltwater and alkali need to circulate for some time in order to wash away the metal ions, organic substances, and other impurities that have accumulated on the membrane surface; as a result, the pressure in the tank is lower when operation resumes. After driving for about a week, the impurities on the membrane gradually return to their original level, so the voltage keeps rising. Since starting and stopping the operation can cause some damage to the membrane, the tank pressure will be slightly higher after it stabilizes once operation resumes, compared to the original pressure.