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Dear colleagues: In the production of ion-exchange membrane caustic soda, positive and negative pressure water seals are often installed in the ion-exchange membrane electrolysis process and chlorine treatment process to protect the ion-exchange membrane as well as the pipes of drying equipment. The chlorine gas from the positive pressure water seal is directed to the chlorine accident tower, while that from the negative pressure water seal is released into the atmosphere. However, in actual production, it often happens that the chlorine drying and transportation system first experiences a high negative pressure followed by a high positive pressure, resulting in a large release of chlorine gas. At such times, the operators in the control room and on site are unaware of a chlorine leak, which can lead to safety and environmental incidents. Especially when there is a malfunction in the pressure transmitter in the chlorine accident tower, a large amount of chlorine gas flows back to the drying tower, causing significant leakage from the chlorine water seal in that tower and resulting in a chlorine leak accident. Currently, plants usually use one positive pressure water seal and one negative pressure water seal; the chlorine gas from the positive pressure water seal is sent to the ion-exchange membrane chlorine accident tower, while the height of the water level in the negative pressure water seal is typically around 500 mm (the exact value varies depending on the specific process). A high negative pressure can draw the water out of the water seal, allowing air to enter the chlorine system. If water is supplied to the water seal properly at this time and the chlorine drying and transportation system operates normally, the negative pressure in the drying tower system can be gradually controlled, preventing chlorine gas from escaping through the water seal. But in case of abnormalities, such as a large amount of chlorine gas flowing back from the turbine outlet to the drying tower system, a high positive pressure will occur, leading to a large release of chlorine gas. If water is not added to the water seal in time, or even if water is added but the pressure of the chlorine gas flowing back to the drying tower is too high, exceeding the water level in the water seal, then a large amount of chlorine gas will leak out. I would appreciate it if any colleagues could share diagrams related to chlorine water seals. I previously saw and downloaded such diagrams on the Haichuan Forum, but I can no longer find them. Please provide them again. Thank you, WHS, 20180619