Process issues in catalytic reforming
Thread Content
This post was last edited by sxf1028102800 on 2024-1-7 at 17:17. Hello everyone, I have a question regarding reforming. In catalytic reforming, the pre-hydrogenation naphtha fractionation tower separates light naphtha. Are the main components of light naphtha C5? In the reformation section, there is a depentanizer that removes fractions with boiling points below C5. Since the naphtha distillation column for pre-hydrogenation earlier in the process already produces light naphtha, why is there still a depentanizer needed to remove fractions with boiling points below C5? Isn’t this a repetition? If you know anything, please let me know. Thank you
In the catalytic reforming process, the pre-hydrogenation naphtha fractionator does indeed separate light naphtha. The main components of light naphtha typically include light hydrocarbons ranging from C5 to C6, but it doesn’t necessarily contain only C5. The pentane removal column is likely installed to further purify the reforming feed, ensuring that C5 and lighter components are effectively removed. Even though the pre-hydrogenation fractionator separates out light naphtha, some C5 components may still remain in the distillate; furthermore, this step may not completely separate all components below C5. The depentanizer can further improve the separation efficiency and better control the quality of the feedstock entering the reforming reactor, thereby preventing excessive amounts of light components from affecting the reaction efficiency and the stability of the catalyst. Therefore, although these two towers overlap to some extent, they each have their own purposes and significance in terms of manufacturing processes. .
For more details, please refer to Catalytic Reforming Processes and Engineering (PDF version) (attachment updated and available for download): https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=638789&shareuid=301199
It’s very simple: the naphtha separation tower at the front is used to separate the light hydrocarbons with molecular weights below C6, including but not limited to C5, as well as some even lighter components； Since the main purpose of reforming is to produce aromatics and gasoline blending components, and the reforming reaction is one in which the number of carbon atoms remains unchanged, hydrocarbons with fewer than 6 carbon atoms do not react in the reforming system and require energy consumption; therefore, it is necessary to remove such hydrocarbons before the reforming process. The reason there is also a depentanizer in the reforming section is that after the reforming reaction, due to the effect of high temperatures, some cracking and pyrolysis reactions inevitably occur, producing small-molecule hydrocarbons. Since the useful product for blending into gasoline components is the C5+ fraction, a depentanizer is still required.
After pre-hydrogenation to remove impurities and saturate olefins, the light fractions are separated to ensure that fractions above C5 enter the reforming reactor. However, during the reforming process hydrocracking occurs, a reaction that breaks down larger hydrocarbon molecules into smaller ones; as a result, light components below C6 reappear. Therefore, an additional depentane column is used to remove these components below C5.
Yes, mainly there is a cracking reaction