Minor issues during hydrogenation shutdown

It is necessary to determine whether desulfurization of the circulating hydrogen should be stopped in advance before hot hydrogen is introduced with oil; furthermore, it is important to know whether waste hydrogen discharge is enabled when hot hydrogen is present with oil. These two factors can lead to a gradual decrease in hydrogen sulfide levels in the circulating hydrogen.

Shut down hydrogen desulfurization; minimize the emission of waste hydrogen

Another measure is to dissolve it in high-pressure gas, which can appropriately reduce the high-pressure conditions and thus decrease the dissolved hydrogen sulfide. During the hot hydrogen oil-carrying period, the hydrogen sulfide content in the circulating hydrogen keeps decreasing; only the rate of this decrease can be controlled, but it cannot be prevented from decreasing.

It is not feasible to end the hot hydrogen operation with oil still present, especially when there are maintenance tasks on the reaction system or when it needs to be shut down for an extended period. Having residual oil not only poses obstacles to maintenance and creates safety issues but also is harmful to the catalyst, as it can affect its strength. Most hydrogenation units have measures for sulfur supplementation; it is recommended that you add a sulfiding agent (dimethyldisulfide or carbon disulfide) to the system.

I just want to know if a vulcanizing machine can be added during the process of adding oil to hot hydrogen. I just saw someone above say that DMDS should be used; isn’t DMDS used during the pre-vulcanization phase as a catalyst? Moreover, the equipment would need to be filled with vulcanizing oil again, so wouldn’t all that preliminary work be in vain? Additionally, since oil is only present on the catalyst, reduction of the sulfiding machine basically does not occur. When the hydrogen gas contains oil and the hydrogen sulfide concentration is below 1000 ppm (the standard for our facility), it is possible to end the process of using hydrogen gas with oil in it ahead of time. If the oil is not something like wax oil, it will not cause any damage to the catalyst; however, if it is wax oil, it is unlikely that the hydrogen sulfide concentration will be too low. In such cases, I believe it is necessary to replace the oil with a lighter type of oil before proceeding with the normal shutdown procedures. This is just my personal opinion; everyone is welcome to discuss it