Interlock between the electrolyzer and the chlorine pressure pump

If one or two chlorine compressors in the electrolyzer fail, it will not trigger an interlock shutdown; however, as long as you keep the chlorine pressure under control and ensure it does not exceed the specified value, no interlock shutdown will occur. Of course, it is often the case that after the electrolyzer shuts down once or twice, the chlorine pressure can no longer be controlled, which leads to a complete shutdown of the entire system. If the entire electrolyzer shuts down, the chlorine pressure controller will definitely shut down as well.

It’s possible in theory. If it is a short-term stop followed by resumption of operation, the compressor does not need to be stopped; the shut-off valves for the chlorine and hydrogen compressors should be closed, the bypass valve for the chlorine emergency pipeline should be opened, and the hydrogen should be vented before use. However, when domestic compressors suddenly disconnect from the system under high-load operation, the adjustment range of the automatic control circuit is limited, and the instantaneous air supply volume may not meet the requirements for the operation of the unit. Furthermore, during electrolysis shutdown, if the valves related to the hydrogen-chlorine system do not act instantly and in a timely manner, it can affect the pressure in the main pipes and even the electrolysis unit; therefore, as a risk prevention measure, it is standard practice to interlock the compressor after the electrolysis process is stopped. Just my opinion; feel free to correct me!

The last edit to this post was made by huawei on 2010-6-7 at 09:08. When the electrolysis is stopped and direct current is cut off, PCV216, PCV226, as well as PCV218 which is connected to the waste gas treatment system, and PDV228 for hydrogen release, will all activate in a sequential manner. It is not clear whether you have designed emergency shut-off valves ZV219 and ZV229 leading to the hydrogen chloride treatment. Generally speaking, if only the direct current supply for electrolysis is turned off while the chlorohydrogen process continues to operate, there is no need to shut down the chlorine compressor and hydrogen compressor immediately. If power is restored to the electrolysis process after a short period of time, then there is absolutely no need to stop those compressors either; one can simply proceed with the preparations for restarting the operation. Personally, I think it’s not very advisable to shut down the chlorine compressor via interlock. However, for large chlorine compressors, there is indeed a situation where gas replenishment is not fast enough; to protect these expensive compressors, many manufacturers design systems with interlock shutdowns that direct the waste gas to the waste gas treatment process – this is also a compromise solution. The poster needs to take into comprehensive consideration factors such as the scale of their products, the selection of chlorine compressors, and the equipment that requires priority protection. However, when the direct current supply is suddenly interrupted during electrolysis, significant fluctuations in the pressure of hydrogen chloride occur frequently. Especially in the case of chlorine, since the chlorine compressor continues to operate under load, a large positive pressure difference is generated in the electrolyzer, and the instruments often fail to adjust quickly enough. Close human attention and careful operation are required; instruments are not infallible. Conversely, if the chlorine compressor experiences shutdown issues, careful consideration must be given to the interlock with electrolysis.

We have emergency shut-off valves ZV219 and ZV229

When electrolysis is completely stopped, the chlorine compressor and hydrogen compressor should also stop automatically as a result of this interlock. The chlorine gas from the electrolysis system is removed through a chlorine treatment unit, while hydrogen can be vented before the hydrogen scrubber; this approach helps to protect the ion exchange membrane from being damaged. If driving again shortly after normal parking, the chlorine compressor and hydrogen compressor can continue to operate after the current in the electrolysis process is reduced ； If parked for a long time, it will be shut down.

Reply to 6# Junyi: The safe approach is not to use interlock shutdown for the chlorine compressor (the main electrolytic chlorine pipeline has a negative pressure water seal, which can keep the pipeline pressure from dropping too low)； The hydrogen water ring pump must be stopped to prevent air from being drawn into the system through the main pipe and vent pipe** ； During the electrolysis process, it is advisable to equip the chlorine compressor with an automatic reflux mechanism to ensure stability in the chlorine system. (The 3K compressors used by our company can automatically close or reduce the inlet guide vanes, and an automatic reflux function is available to prevent surging and protect the chlorine compressor.) ； The electrolytic hydrogen main pipe automatically replenishes nitrogen to maintain stable system pressure and displace hydrogen ； ）