Several questions about gasoline hydrogenation
Thread Content
I’m a beginner seeking advice from the experienced teachers: 1. Why must the feed for gasoline hydrogenation come directly from the catalytic cracking unit? If there is a problem with the catalytic unit, it will affect gasoline hydrogenation as well; isn’t it possible to use feed from the storage tank instead? 2. When catalytic gasoline enters the unit for pre-hydrogenation, it needs to be mixed with fresh hydrogen, and for the subsequent hydrogenation and desulfurization of heavier gasoline fractions, recycled hydrogen is used. What determines the amounts of fresh hydrogen and recycled hydrogen that should be used?
First, it’s probably due to issues with your company’s processes; otherwise, it’s because you don’t have storage tanks or nitrogen sealing.
1. If energy consumption and other issues arise in storage, transportation, and material delivery, this will ultimately need to be coordinated by the production department. 2. Regarding the amount of hydrogen used, the hydrogen-to-oil ratio needs to be taken into account, as well as whether the pressure of the recycled hydrogen is sufficient for the requirements of the pre-hydrogenation reactor. Additionally, it is necessary to consider whether the operation of the fractionation tower after pre-hydrogenation can ensure an appropriate sulfur content in the light oil
Are you saying that oil storage tanks require nitrogen sealing?
May I ask what parameters are used to determine whether the pressure of the recycled hydrogen can meet the requirements of the pre-hydrogenation reactor?
The first issue should be that of hot feeding, in order to save energy; however, even with direct feeding, there is still a buffer tank before the material is fed in.
The second question relates to a different process from our gasoline hydrogenation unit, so it’s difficult to answer. ;P
Right. The feed tank for hydrogenation requires a nitrogen seal
1. It’s probably because your company is short of storage tanks; the design didn’t take into account the need to have separate storage tanks. Feeding from the storage tank is quite sufficient, and it can also reduce fluctuations. 2. Personally, I believe that the choice between fresh hydrogen and recycled hydrogen should be determined through a comprehensive balance based on the hydrogen consumption of the two types of feed materials.
Does your company use Prime-G+ technology? If that’s the case, it’s likely due to this reason: 1. When gasoline is stored in a storage tank for an extended period of time, in the absence of a nitrogen blanket, many dienes, gums, and other substances that can lead to coking are formed. Dienes readily polymerize, resulting in coking. 2. Very little H2 is used in preprocessing ； H2S is inevitably present in recycled hydrogen, and H2S reacts with olefins to form thiools; the purpose of pretreatment is to remove these thiools. It’s just my personal understanding; please feel free to correct me
The pressure of the recycled hydrogen in your system must not be even slightly lower than the pressure in the pre-hydrogenation reactor, right?