Discussion
Thread Content
Please discuss a few points. First, why is it necessary to add oil enthusiastically? It should be stored in the reactor after cooling, and it will be added automatically when heating up again to restart the process. Second, why not add oil first and then raise the temperature to establish a cold cycle? How would it be to raise the temperature later?
My opinion: First, as long as operations are halted and no catalyst is loaded or unloaded, it is not necessary to perform a hot hydrogen purge with oil present. Second, heat the oil first and then raise the temperature to establish a cold cycle; it is completely fine to raise the temperature later.
Has anyone done such an experimental operation?
I’ve done them all. 1. The catalyst is not prone to spontaneous combustion under the protection of an oil film, so it can be placed in a reactor without any problem. 2. Many catalysts are pre-sulfided in a wet method, with the oil added first and then the temperature increased. Since the airtightness testing of high-pressure hydrogen is carried out at a certain temperature, the oil inlet temperature is generally not room temperature.
1. Hot hydrogen with oil is generally used only during shutdowns for maintenance. If the heat exchanger needs to be repaired or the catalyst needs to be replaced, this method allows most of the oil inside to be removed, facilitating the maintenance work. During normal operation, hydrogen circulation takes place, the reaction temperature rises, and feed is added. You’re referring to this, right? This is actually different from hot hydrogen with oil; the temperature in the case of hot hydrogen with oil is higher, and it depends specifically on the final boiling point of the raw material, with the process taking around 8 hours. It takes a bit longer. 2. What you mentioned, namely heating after adding oil first, works as well, but what exactly is the low temperature in the cold cycle? The reactor temperature must not be too low, as the flanges expand and contract with temperature changes, which can lead to leaks. Also, the system pressure is not very low when oil is being introduced, and since the reactor temperature is very low, aren’t you concerned about austenite tempering? Raising the reactor inlet temperature before feeding oil is done to shorten the startup time; if cold oil enters after the feed pump is started, it will lower the reactor inlet temperature. The temperature still needs to be raised at this point.