What are the effects of leaving an ion exchange membrane in a stopped state for a long time? (Examples)
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This post was last edited by sunjl1981 on 2013-1-6 at 22:02. Reason: Due to the industry crisis, the facility was not operating at full capacity; as a result, the electrolyzer had to remain shut down for long periods of time! After it was restarted, the cell voltage rose significantly. (It had been shut down for three months.) Maintenance: During the shutdown period, routine maintenance was carried out in accordance with the operation manual – the membranes were cleaned once a week to keep them moist. Nitrogen was used to fill the cathode tank to prevent air from entering. Observation: When the electrolyzer was restarted again, the cell voltage increased substantially. At first, the cell temperature was not very stable; its rise was just a bit slow, but it wasn’t extremely unstable. After about ten hours, the cell temperature became similar to that of the other cells, but the cell voltage continued to rise, by around 2V per day. Currently, the average voltage per cell has reached 3.17V – this is the voltage level achieved by the other cells after nearly a year of operation, while this particular cell has only been in use for two months. Equipment: Beihua Machinery electrolyzer + Asahi Kasei membranes. I would appreciate it if experts could analyze and explain what might be the cause of this phenomenon????:handshake This post was last edited by yzhms on 2009-3-2 at 12:14.] hcbbs !!
1. The quality of the secondary brine is unsatisfactory. 2. During shutdown, other tanks were left open; the chlorine system was not properly isolated (no blind flanges were used), and there were leaks in the valves, which caused chlorine to flow back into the electrolytic cell where it reacted with water to form hydrochloric acid, resulting in acidification of the membrane. 3. The anode-cathode wires, instruments, and valves are damaged; iron ion levels are severely excessive, contaminating the electrolytic cell. 4. The nitrogen is too dirty; it contains rust.
Do you mean that only one tank was stopped, and it was only the voltage of this tank that increased? In the past, whenever an interlock caused the system to shut down, the voltage of the tanks would rise, but it would drop again after some time; overall, however, there was still a tendency for the voltage to increase
Every time the vehicle is started after stopping, there is another phenomenon of the rail voltage rising and then falling, before it stabilizes. Strengthen daily operation and maintenance, and ensure proper monitoring of tank voltage.
Insufficient maintenance after parking; the membrane should be removed and soaked to ensure it is properly protected, which will improve the situation once driving resumes.
My question should be quite clear. Does anyone with experience have anything to say about this situation where the slot voltage rises and doesn’t drop again? This slot is actually new, yet its voltage is 3–4 V higher than that of slots that have been in use for over half a year. What does this indicate? What could be the reason?
Although film-coating maintenance was carried out after stopping the tank operation, changes in temperature and humidity caused chemical changes to the iron ions and other substances adsorbed on the film; when operation resumed, the resistance increased, which led to an rise in the tank voltage.
It is recommended to analyze not only the reasons for the parking issue, such as whether the material of the components is of suitable quality or whether the saltwater flow rate is correct, but also to start by analyzing and comparing the data from the moment the vehicle was started. Is there a possibility of iron ion contamination?
The original poster still hasn’t made their question clear: Does your current level reach full load within a day? Is the voltage still rising after the load has been properly increased and the tank temperature has stabilized? (This happens when the load is too high; it would be strange if it didn’t occur under high load conditions.) The original poster only provided the voltage value; for those who have never encountered this problem, it would take a genius to be able to analyze the situation and come up with a solution. Also, if you did follow the operating procedures provided by Asahi Kasei when parking the vehicle, and now the voltage while driving has risen to such a high level with no sign of it dropping, then you should immediately consider contacting Asahi Kasei. This post was last edited by haining on 2009-3-12 09:28]
It is likely that the gas valve of the electrolyzer that stopped operating was not closed, allowing chlorine to penetrate and causing acidification of the ion exchange membrane.
We are comparing the current data with those from when we first started driving; the current figures are really not comparable to those from back then – the difference is quite large. We have been trying to find the reasons, but no definite conclusion has been reached yet.
Reply: haining – Our tank is filled up within a day, so its temperature certainly isn’t as high as that of the other tanks; it’s about 5°C lower. The voltage in that tank was similar to the values at the start of operation, but in the afternoon we noticed that the voltage kept rising gradually, by about 1–2V per day, until it reached its current maximum level. By now, the tank temperature has stabilized. We later discussed this matter with the Japanese people; they came to take a look as well but didn’t seem to offer any useful insights. We’re still trying to find out the cause. Last edited by limingshuguang on 2009-3-17 20:49
Friend, you said it’s possible that such a thing could happen, but it hasn’t happened here as you said. We do a very good job in protecting the battery cells.
According to the original poster, the moisture retention of the ion membrane should be fine. The main reason may be an excessive shutdown time of the cell, resulting in residual current in the cell; the reverse potential then causes corrosion of the cathode and anode electrodes. Prolonged parking should be considered from both the membrane and electrode perspectives.
It is recommended that the poster check whether the coating of the electrolyzer is damaged, as well as whether the membrane has been damaged during the shutdown period.
What I mean is to start creating a voltage variation curve from the moment driving begins, to see how it changes before stopping, and how it changes after starting again; by creating a statistical curve, we can look for clues. By comparing the changes before and after stopping, and then waiting for an opportunity to stop the vehicle and verify things, we might obtain the answer you need. Discussing things like this on forums may help you solve the problem, but it’s mostly based on guesses and experience, and doesn’t really aid in resolving the issue.
I hope the original poster can post your latest progress so that we can continue the discussion. As well as recent changes in parameters such as the voltage of the electrolyzer.
Yes, there should be no problem with wetting the membrane on our end. Could it be due to the long parking time? A reverse potential might occur right after parking, but after so many washes, it shouldn’t have a significant impact anymore. The tank is now in operation, and the tank voltage is higher than at the beginning, with no sign of it dropping.
I agree with what you said, friend, but it seems like we don’t know where to start at the moment. We’re in the process of conducting arguments and experiments.
Okay, I’ll let you know if there are any new developments. The cell is currently in operation, and the voltage across it remains quite high; it doesn’t seem to be dropping. We’ve now used a new cell to compare it with the current one, but there isn’t much difference. It seems that the problem isn’t with the cell itself, but rather with the ion membrane.
As the original poster said, it seems that there is an issue with the quality of the saltwater. 1. Is the secondary brine qualified? (Exiting the tower) 2. Are the materials of the secondary brine pipelines, equipment, and instruments appropriate?