Caustic soda chain

I believe the sequential devices for caustic soda include: 1. Brine flow rate into the tank； 2. Flow rate of circulating alkali in the tank ； 3. High voltage high and low voltage low interlock ； 4. Chlorine pressure ； 5. Hydrogen pressure ； 6. Chlorine compressor interlock ； 7. Resin column pH value interlock ； 8. Electrical appliance chains, etc

Chlorine pressure, hydrogen pressure, hydrogen-chlorine pressure difference, current upper limit, anode fluid flow rate, cathode fluid flow rate, EDIA, instrument air pressure,

Upper limit for chlorine pressure, upper limit for hydrogen pressure, upper (lower) limit for the pressure difference between hydrogen and chlorine, upper limit for current, lower limit for anode solution flow rate, lower limit for cathode solution flow rate, upper (lower) limit for EDIA, lower limit for instrument air pressure, upper limit for grounding voltage, shutdown of chlorine compressor, shutdown of hydrogen compressor, malfunction of the dilute brine valve, level of caustic soda tank, level of fresh brine tank

The caustic soda plant is not complex, and its level of hazard is not that high; there’s no need for so many interlocks. Simply enabling and disabling the plant is sufficient, with hierarchical alarms in place for timely handling. Some of the imported devices, after being in use for a while, had many of their links removed, which is also a waste. However, automatic adjustment of some critical materials is essential; human reaction times can be slow at critical moments.

I disagree with the opinion from the 5th floor. In my view: 1. Having many interlocks does not mean that there will be many start-up and shutdown operations; during the commissioning and trial production phases, the number of such operations might be higher due to issues related to electrical equipment and instruments, but once these problems are resolved, continuous and stable production can be achieved； 2. More interlocks mean more protection mechanisms: Most ion membrane electrolysis units are imported, especially the ion membranes themselves, which are expensive. For a plant with a capacity of 100,000 tons, around 700 membranes (each with an area of 2.7 square meters) are required; each membrane costs over 10,000 yuan, resulting in a total cost of nearly 8 million yuan for the membranes alone, not to mention the electrolyzers made from precious metals. The interlocks in ion-exchange membrane caustic soda systems are primarily designed to protect the cells and membranes. If interlocks related to pressure differences, chlorine pressure, hydrogen pressure, brine flow rate, etc., were removed, those who have experience in production can imagine what would happen If one has a thorough understanding of the ion-exchange membrane caustic soda system, who would dare to simply decide to eliminate these interlocks? 3. Numerous interlocks imply a high degree of intrinsic safety: Chlorine, hydrogen, and caustic soda are all substances that are harmful to humans, highly toxic, or flammable and explosive. The ion-exchange membrane caustic soda system takes these factors fully into account during its design, such as the use of negative pressure for hydrogen, as well as interlocks between chlorine compressors and electrolysis cells. Without such interlocks, could the safety of the operators working there be properly ensured? Can it fulfill its social responsibilities toward the local residents? This situation has not occurred before. 4. Many interlocks mean a high degree of automation, which in turn leads to higher labor productivity: a device that relies solely on manual operation does not have any interlocks. Interlocking is based on a high level of automation; it applies to the entire system. In foreign countries, the number of operators is less than one-third of ours. It’s easy to imagine that without interlocking, could they do such a thing? In short, I believe that interlocks in ion-exchange membrane caustic soda systems are absolutely necessary; they should not be removed lightly. Instead, it is important to thoroughly consider the purpose and function of each interlock so that its importance is well understood by everyone. After each maintenance session, system interlock tests must be carried out. During normal operation, safety and environmental protection devices should be tested regularly to ensure they are operational and can respond appropriately. This post was last edited by wlntjs on 2008-1-29 09:42]

Everyone has forgotten the oil pressure interlock of the electrolyzer

There is no interlock for oil pressure; only an alarm is given.

Brine feed to tank, catholyte flow interlock

1. Saltwater flow rate into the tank； 2. Flow rate of circulating alkali in the tank ； 3. High voltage high and low voltage low interlock ； 4. Total chlorine pressure ； 5. Total hydrogen pressure ； 6. Chlorine compressor interlock ； 7. Electrical interlocks; 8. Brackish water; 9. Level of the alkali tank fluid; 10. Some important machines; 11. Pressure of chlorine gas; 12. Pressure of hydrogen gas; 13. Voltage of the individual tank. There are others as well, but with too many interlocks, it’s easy for the system to shut down