Wax oil hydrorefining: What to do if there is a disruption in the natural gas supply to the feedstock heating furnace? ?

My understanding is that when the time is short, reduce the volume and run it in a loop; once the time becomes longer, stop it. Oil inlet replacement is used to prevent the oil being processed from having high viscosity and from solidifying.

Paraffin oil definitely has a very high viscosity – it will solidify within the pipelines if the furnace is shut down for even a short period of time. Therefore, the question to consider is whether to replace it with oil of lower viscosity or to use hot hydrogen to carry the oil away. Moreover, I believe that even if the shutdown time is short, the duration of the large-scale circulation is sufficient for paraffin oil to solidify within the pipelines

Generally, when there is a disruption in the refinery gas supply, we immediately switch to oilfield natural gas. However, in cases where fuel gas is the only option available and there is a disruption in its supply, if the duration of the disruption is short, we reduce the flow rate and switch to a lower-quality feed; if that isn’t possible, we stop the feed pump, allow hot hydrogen to carry oil through the reaction section, and implement a short-cycle operation for the separation process. It is essential to remove the wax oil from the reaction piping and inside the reactor; otherwise, it will cause a lot of trouble. Some time ago, there was an explosion at Fujian Tenglong Aromatics; when the wax oil hydrogenation unit stopped operating abnormally, the oil was not removed from it, and as a result it all condensed inside the reactor. It took a long time to get the unit up and running again.

In a short period of time, if hydrogen is mixed in front of the furnace, there should be no problem; but over a long period of time it definitely won’t work. It’s better to switch to diesel for replacement and then use a recycling system

If recovery is not possible over an extended period, operations must be halted and diesel must be used as a substitute. However, during this process, the temperature of the reactor continues to drop. If recovery can be achieved in a short time, it is possible to hold on for a while by reducing the amount of cold hydrogen used. The temperature of the feed oil before it enters the furnace after being replaced in this unit is 260–270 degrees; the operator can make some adjustments based on the specifics of their own unit

Taking everything into account, if the time available is short, it is possible to reduce the amount of oil used; if the time is longer, oils with low viscosity can be utilized. In such cases, the feed to the unit should be stopped and purge hydrogen should be introduced to carry the oil away using hot hydrogen. However, if the viscosity of the oil is too high, this method is likely not effective, and it will be necessary to use oils with lower viscosity and lower freezing points for replacement, otherwise the waxy oils will solidify within the pipelines in a very short time – the consequences are obvious. . . It's just my personal opinion; feel free to discuss it together