What the heck is CO detected in the interlayer of the LNG liquefaction cryogenic tank AB?

This situation is indeed a bit strange, but several possible reasons can be inferred: 1. **Local leakage or contamination** CO was detected in the middle and top parts of cold box B, but not in cold box A, which suggests that the problem may lie inside cold box B. It may be that there is a slight leak in some component (such as a pipe or weld), allowing external air containing CO to penetrate into the interlayer, or contaminants may have been introduced during equipment maintenance. 2. **Formation through chemical reactions** Although the feed gas and mixed refrigerant do not contain CO themselves, local chemical reactions may occur inside the cryogenic tank under specific temperature and pressure conditions. For example, hydrocarbons (such as methane and ethylene) may undergo incomplete oxidation reactions to produce CO under the action of metal catalysts (such as rust on the inner walls of equipment). Certain areas of the B cryogenic tank may have such reaction conditions. 3. **Detection or sampling issues** Check whether the sampling points in Chiller B are contaminated, or whether there are errors in the detection equipment itself. It cannot be detected in the cold box; it may also be due to an inappropriate sampling location, which prevents the actual CO from being captured. **Suggested troubleshooting steps: ** - First, verify whether the testing equipment and sampling process are reliable ； - Check the sealing integrity of the B cryogenic tank interlayer, focusing on the middle and upper areas ； - Monitor whether there are any abnormal fluctuations in the operating parameters of the equipment (temperature, pressure), especially in the areas related to the B cryogenic tank ； - If necessary, shut down the machine to conduct an internal inspection of the B cryogenic tank to check for localized overheating, corrosion, or accumulation of impurities. In short, CO is unlikely to originate from the raw materials or refrigerant; it is more likely to result from external infiltration or internal reactions, so a thorough inspection of cold box B is necessary. .

The A cold box uses the same nitrogen supply; everything in the A cold box cannot be measured due to this single pipeline system

With nitrogen supplied to both AB cold boxes, no reading can be obtained from box A

I recommend increasing the nitrogen flow in the interlayer of cold box B; if replacement is possible, do so, and then conduct tests and monitoring for a period of time