Unloading of methanol synthesis catalysts

We do not perform passivation during unloading; during this process, nitrogen is supplied continuously. First, the discharge port at the bottom of the synthesis tower is opened to unload the catalyst, and water is sprayed on the catalyst being unloaded to remove any flammable materials around the synthesis tower. Filling the ceramic balls is relatively slow (about 2–3 days, as it is necessary to measure the height of each ceramic ball in the tubes), while the catalyst can be filled in just 1 day (24 hours of work).

Reply to 2# feiyuezhang: Was there a temperature drop when the catalyst was unloaded? What was the temperature? It's 100 degrees here; the oxygen content at the inlet of the passivation process is 0.6%, and the process was carried out for only 24 hours

Do you check whether there are scabs on the tube wall after removing the catalyst?

Reply to 2# feiyuezhang: Theoretically, this is possible (using a tubular synthesis tower), but how can we ensure that the catalyst is completely removed? If it’s incomplete, manual intervention is definitely required to fix it. At this point, air must be used for displacement before entry is possible; even at a low temperature of 40 degrees, can it be ensured that the catalyst does not oxidize at all? We have never tried this with synthetic catalysts; for the hydrogenation catalysts used in sulfur recovery, after lowering their operating temperature, we simply drained them. It wasn’t watered at all, mainly due to the low cobalt and molybdenum content.

Reply to 5# Shouhou: Our factory is about to replace the catalyst, but it’s not clear whether it will be possible to unload it smoothly

Reply to 6#: I don’t know you. Are you planning to release it without passivation as well? Is it a tubular synthesis tower? How high is the catalyst layer in the heating promotion layer?

For 45 tons, it’s better to carry out passivation; otherwise, it won’t be possible to handle it after unloading. The internal temperature will be very high due to oxidation. If the catalyst isn’t incinerated, the risk of fire is low, but it’s still advisable to use water or oxygen for passivation. As for whether it can be completely unloaded, it depends on whether the operations are stable on a regular basis and whether there have been any instances of overheating or overpressure. For 45 tons, it takes around 30 hours to complete the unloading process. It’s essential to ensure that the internal temperature drops below 40°C during unloading

It’s sufficient to cool the synthesis tower to 50°C; feed deionized water into the drum as early as possible, and use nitrogen circulation in the compressor. This approach allows for faster cooling, and there are no issues with unloading the material. At first, sparks may appear from the catalyst, but watering it down will resolve the problem. As unloading continues, no further issues will arise. Find a professional loading and unloading company; they have advanced equipment, including air compressors with long hoses, which are used to extract both the catalyst and ceramic balls using vacuum pumps.

Reply to 9# feiyuezhang: If the production process allows enough time, it is advisable to carry out passivation treatment first before removing the catalyst. If time is limited, the catalyst can be cooled through the standard process until it reaches room temperature; at that point, the lower end cap of the synthesis tower can be opened. It is also essential to continuously supply nitrogen to the tubes inside the synthesis tower. When the catalyst is removed to the ground, industrial water should be used for cooling it. It is necessary to avoid a situation in which, after the catalyst comes into sudden and extensive contact with oxygen in the air, the large amount of heat generated during copper oxidation cannot be dissipated in time, leading to an increase in the catalyst’s temperature. This excessive heating can cause the catalyst to catch fire on its own. Because synthetic methanol catalysts are nanomaterials, they generally possess this characteristic. Waste catalysts must be packaged and transported in iron drums or packaging bags with tin-plated or similar materials on their inner surfaces. Be sure not to forget to spray water. Catalyst recycling manufacturers generally know these principles. A couple of days ago, our company carried out catalyst loading, and I attended a bidding meeting.

Which unit are you from? It seems that watering it more and leaving it for a few more days will suffice; no special packaging is needed, right?