Fire at the cathode outlet? Details of the production incident
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This post was last edited by sunjl1981 on 2013-1-7 at 00:12. Reason: There was a slight leak in the cathode outlet hose during operation, so it needed to be replaced with a new one. Background: During the replacement process, sparking occurred because the special wrench came into contact with the nut of the adjacent hose. On-site situation: After detecting the leak in the cathode outlet hose, we consulted the relevant supervisors and decided to reduce the current level before replacing the hose. After reducing the current, appropriate measures were taken, including cyclic replacement and isolating the electrolytic cell. During the replacement, since the special wrench for the hose had insulation only on its handle, and the distance between the outlet hose and the other hoses was quite small—only about 3 mm—the wrench accidentally made contact, resulting in sparking; this led to a fire at the cathode outlet. The personnel on site reacted quickly and managed to extinguish the fire using a fire extinguisher. Fortunately, the replacement process took a long time, and the electrolytic cell contained mostly nitrogen with only a small amount of hydrogen, so no serious damage occurred. Note: After isolation, the pressure in the electrolytic cell was released; then the anode side was opened to remove harmful substances, while the cathode side was filled with nitrogen to evacuate any remaining gases. (DP-234 was used to fill the cell with nitrogen.) Post-event analysis: If the polarization power supply had been turned off at that time, would it still have caused sparking and a fire at the cathode outlet? Follow-up: Later, a pinhole-like defect appeared in the anode outlet hose, leading to the leakage of a small amount of salt crystals and chlorine gas. This time, we made sure to turn off the polarization power supply before replacing the hose. Yet, due to the extremely small distance between the hoses, sparking still occurred. This shows that whether or not the polarization power supply is turned off, sparking will occur as long as there is a short circuit between the hoses. It’s possible that turning off the polarization power supply reduces the severity of sparking. All these issues indicate that there are still imperfections in the electrolytic cell that require technical improvements: although the wrenches are insulated, over time, repeated use for tightening nuts can cause the insulation to break down. Additionally, the very small distance between the hoses represents another potential hazard. If anyone has any good solutions, please share them with us.:handshake This post was last edited by limingshuguang on 2009-4-27 at 11:34. ] # hcbbs
This accident occurred because short-circuiting between the unit cells via wrenches caused arcing, leading to the combustion of hydrogen! Firstly, this leakage should be addressed by treating the electrolyzer’s effluent. The polarization power supply in question has not been removed; therefore, the voltage in the cell should be between 1.6–1.8 V. Moreover, a slight level of electrolysis is still taking place, which increases the voltage drop between the electrolyzer cells and makes sparking more likely! Even without polarization, it cannot be processed immediately due to the presence of a back voltage in the short term. It should be the cathode; how could there be a small amount of chlorine leakage? ! This type of handling must be done using insulated wrenches! This post was last edited by nanren2 on 2009-2-23 18:52]
After draining the electrolyzer, measure whether there is still voltage present. If there is no voltage between the cell and ground, and no spark occurs when using a wrench to make a connection, then it is safe to proceed with operations. This post was last edited by shizhiyong001 on 2009-2-24 09:23.]
During liquid discharge, nitrogen is injected at the tail end of the tank while the head end is vented; the cathode chamber is kept under positive pressure. After several cycles of treatment, discharges still occur, but there is no fire
We discovered this problem when the current had just started to rise; therefore, the supervisor suggested not draining the liquid but instead isolating the cell for treatment. Yes, there was polarization at that time, with the cell voltage around 1.6 V. I wondered whether stopping the polarization process and waiting for some time would help improve the situation, or whether it would be better to wait until the cell voltage dropped to a lower level before taking action.
I don’t think it’s necessary to drain the electrolyte tank in order to replace the outlet pipe. My approach is to stop the polarization current and cease the circulation of the electrolyte in both the anode and cathode chambers; I isolate the gas phase of a single cell from the rest of the system, empty the outlet pipe, and fill the cathode with nitrogen. First, I remove the nuts on the pipe connections at the main pipe, then those on the connections to the individual cells. When installing the pipes back, I first connect those to the individual cells and then attach them to the main pipe. The same procedure is followed even when only replacing gaskets. The wrench does not need to be insulated; however, people must take precautions (wear insulated gloves and insulated shoes). Mine is a Asahi Kasei battery.
After you end the polarization process, it is necessary to replace the liquid inside the electrolyzer; you cannot simply replace only the hydrogen gas. There is a small amount of hydrogen present in the liquid, and if you do not replace the liquid, the electrolyzer itself will develop its own resistance. The electric charge present in the liquid cannot be completely eliminated immediately. Therefore, it is recommended that you thoroughly replace the liquid after ending the polarization process to ensure proper discharge from the electrolyzer. If this replacement is not carried out, the electrolyzer may remain charged even after the polarization process has been completed, and sparks will continue to occur as long as the two electrodes are in contact. Last edited by limingshuguang on 2009-3-1 10:36
Logically, it should be done as you suggested: drain the water, wash it, replace it for a few hours, and then proceed with further processing. That would certainly be ideal, but completing all these steps takes a considerable amount of time. Sometimes, managers won’t give you that time; perhaps this is just the reality in China.
It is estimated that half an hour is sufficient for gas replacement in the electrolyzer cell – why not? Is there a 10-minute nitrogen purging time? Why not? Why not keep replacing them? Is the rush because the parking time becomes longer? Take it step by step. One foot is 50 taels of silver... the other foot is also 50 taels... 100 taels in total, hehe.
Poster: It seems like you’re violating the rules! How can the above operations be carried out if the electrolytic cell is continuously polarized and no liquid is drained? If the polarization is interrupted and no drainage occurs while performing the above operations, it would be better to disconnect the switch that controls the positive and negative poles. This post was last edited by limingshuguang on 2009-4-27 at 11:36
Whether you use polarization or not, it makes no difference as long as you don’t discharge the battery; it will always start working, unless you discharge it for a long time； Furthermore, without applying polarization, the cathode side can be completely replaced; the cell itself, with its liquid inside, acts as a large capacitor. Last edited by limingshuguang on 2009-3-16 at 11:33.]
The approach used by the original poster is very dangerous; what you’re doing constitutes a violation of regulations. At this point, it’s necessary to use qualified components, and the copper bars must be removed as well
If you were in your company, would you prioritize that? Sometimes, taking risks is necessary when making decisions; experience might be more important than rules in such cases.
The post is sinking – fellow sailors, keep discussing whether polarization should be discontinued When will it withdraw? How long for a refund?
Doesn’t LZ have insulating wrenches? The ones that are entirely made of plastic!:L
What is the logic behind such an order of disassembly and assembly?
I agree with what was said on floor 6: there is no need to drain the fluid when replacing the hoses and gaskets; doing so can sometimes result in greater losses. As long as there is an adequate supply of nitrogen, there should be no problems. If the operating procedures are followed strictly, it is sometimes unnecessary to conduct analyses; it’s important to understand the purpose of such analyses and not to be too rigid about it
1. Disengage the EDIZA interlock. 2. Combine with rectification to reduce the current in that cell. 3. Cycle. 4. Isolate the cell (when isolating the liquid phase, first close the inlet; after the liquid in the outlet has flowed out, then close the outlet valve). Fill it with nitrogen to maintain pressure. 5. Depolarize. 6. Replace the hose. 7. After replacement, initiate polarization, combine the cells, cycle, and then increase the current
There is no need to drain the liquid. Turn on the nitrogen purge; use insulated wrenches and wear insulated gloves, and isolate adjacent nuts with insulating material to prevent discharge.
Have other sailors encountered similar situations? I’m sure they have. Is there a better way that I could share with everyone? The proper procedure is to drain and wash the tank, as draining water once or twice can help reduce static electricity. It is beneficial for both the ion membrane and the electrolyzer, but different approaches may be adopted due to economic and time considerations.
Have you ever seen, when starting up a single-tank system, most of the outlet hoses catch fire and produce a sound similar to that of gunfire? I have seen it happen: during testing, with leaks in 15 locations and a flow rate of 40 L/H, the system was forced to be brought online. As soon as excitation current was applied, the aforementioned situation occurred. The supervisors present tried to flee, but only the manager took immediate action by closing the valves to isolate that tank, which prevented a more serious accident from happening.