Why is the pressure in the hydrogen pipeline 4 Kpa higher than that in the chlorine pipeline?

This is mainly used to control the pressure difference in a single slot as well. It’s also roughly 4KPa. The purpose is to press the ion membrane against the anode. Reduce the channel pressure to minimize membrane vibration. Why 4KPa? That relates to design considerations. It is presumed to be the designer’s theory combined with empirical values. It is related to the membrane strength, surface structure, and the shape and strength of the electrode mesh in the electrolytic cell; the main purpose is likely to keep the membrane in close contact with the anode, thereby reducing the tearing force on the membrane caused by stresses around it. Additionally, too large a pressure difference can also cause deformation of the anode mesh. (Energy saving + consumption reduction + protective film + protective electrode mesh)

Is there anyone who can explain it in more detail? These cells with different pressure differences should also be different, right? Please ask an expert to answer

This may be related to the design of the electrolyzer cell, the pressure that the anode and cathode materials can withstand, as well as process requirements. Let’s start with the positive pressure difference: taking the Asahi Kasei electrolyzers as an example, Asahi Kasei specifies that this value should not exceed 9 KPa; if it exceeds 9 KPa, the electrolyzer shuts down automatically. This is done to protect the anode, as a high positive pressure difference can cause the anode to deform； Speaking of the negative pressure difference, as the membrane is in close contact with the cathode, it suffers from friction between the rigid anode and cathode, which causes pinholes to form. Chlorine then enters the cathode, corroding its layer and dissolving Ni, thereby leading to an increase in cell voltage. Therefore, it is necessary to maintain the pressure difference within a specific range. Taking Asahi Kasei as an example again, a pressure difference of 4 is chosen rather than 3 or 5; an intermediate value may be selected as well. In this way, although the values fluctuate within certain limits, they do not reach the upper or lower limits in such a short time as to cause the system to stop operating. Additionally, different manufacturers may have varying requirements for pressure difference control; I’ve heard that for chlorine processing cells, the required pressure difference is 0.5 KPa. If you want to know more, it’s best to consult the manufacturer. There is another reason: a positive pressure difference can effectively reduce the slot voltage, whereas a negative pressure difference can increase it.