Seeking help with aromatic extraction unit
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The aromatic extraction unit designed by the Chinese Academy of Sciences is for the extraction of monobenzene. The residue oil always exceeds the specified limits; even when the purity of benzene is low, the temperatures of layers 12 and 14 remain above 110 degrees. It’s not possible to bring these temperatures down. What’s going on? I’m afraid to allow the benzene purity to drop too low, as that would result in substandard products
Is there any teacher who can help answer this?
What are the proportions of each feed component? The same issue occurred in our extraction process as well: the designed feed composition should contain about 5% raffinate oil, but in practice only 1–2% was present. The raffinate oil always contained benzene, and no matter how long we tried to adjust this situation, it couldn’t be corrected. Additionally, we previously replaced the trays above layer 15, and the porosity may have increased, resulting in the solvent and reflux being unable to hold back benzene.
It should be closely related to the properties of the feed, especially as changes in the concentrations of benzene and toluene in the feed have a significant impact. Starting double-benzene extraction from single-benzene extraction increases the difficulty of the operation, requiring careful handling.
Toluene may be present in the benzene, or benzene may be contained in the lean solvent; such situations can occur whenever the C6 components are of poor quality
Single-benzene extraction: the feed is a mixed C6 mixture, with a requirement that the toluene content be less than 0.02%. The benzene level in the raffinate oil is too high; it is necessary to control the benzene content in the lean solvent. Additionally, the mass fraction of benzene in the feed to the extraction distillation tower should not be too low. Is this the SED extraction distillation technology developed by the Chinese Academy of Petroleum Sciences?
Hello, are you familiar with the aromatic extraction process in ethylene plants? Is the concentration of benzene in the feed around 50%, and is it around 30% for the feed to the extraction tower in the reforming process?
In terms of process, the purity of the recycled benzene must be ensured first, before considering the purity of the non-aromatic compounds. What was the benzene content in the non-aromatic compounds used for making the sample at that time? What is the temperature of the sensitive plate? What about the feed temperature and the temperature of the lean solvent entering the tower?
For issues of this kind related to manufacturing processes, you can simply take a picture of the DCS, which will make it easier for everyone to analyze it