What is the impact of changes in the feedstock for reformation pre-hydrogenation on plant operation? Experts, please give your advice! ! !
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When changing the tanks for pre-hydrogenation feedstocks, the components of the feedstocks are almost identical (including density, boiling range, alkanes, cycloalkanes, olefins, aromatics, S, Cl, N, As, Pb, Cu, aromatic potential, etc.). But the operating parameters change significantly – is there any reason for that?
The pre-hydrogenation operation adjustments are made by the scheduling department in accordance with the requirements for the products produced by the reforming process; high-octane gasoline is produced, with a low initial boiling point being maintained； For the production of aromatic raw materials, maintaining a high initial boiling point can increase the amount of mixed octane produced through reforming. The specific details are understood by your workshop supervisor; it’s impossible to explain them clearly to you in just one or two sentences online.
I know everything you mentioned. After we change the tank, the oil in that same tank remains unchanged. The operating parameters work fine today, allowing for successful sample preparation, but they don’t work well the next day. Once the parameters for a given tank have been set, they stay unchanged.
Could there be an error in the test results?
I also doubted it, but it can’t keep making mistakes every time, right? I was wondering if there are any other reasons I’m not aware of?
The testing instruments have not been calibrated, so there is a high possibility of errors.
Reforming pre-hydrogenation is primarily used to produce qualified reforming feedstock by removing impurities such as S, N, O, and metal elements from the feedstock, as these can poison the reforming catalysts, in some cases causing permanent poisoning. If the impurity content in the feed increases, the temperature of the pre-hydrogenation reactor can be appropriately increased. The boiling range of the raw material can be adjusted through a distillation tower; for example, to produce high-octane gasoline, the initial boiling point can be kept low ； For the production of aromatic raw materials, it is desirable to have a high initial boiling point. When producing such raw materials, the higher the proportion of aromatics in them, the better – that is, a higher content of the combination of naphthenes and aromatics in the raw material. The higher the final boiling point, the heavier the feed components and the greater the density of the feed, which can lead to severe coking of the catalyst and impose a burden and risks on the regeneration unit. Therefore, strict control is exercised over various parameters of pre-hydrogenation and the feedstock.
Even oil from the same tank can vary, as gravity causes a slight difference in the initial boiling points of the oil at the top and bottom of the storage tank. As the liquid level in the storage tank drops, more light components end up at the top of the pre-hydrogenation distillation tower. At the same time, the impact of the residual oil previously stored in the tank on the new oil, as well as the effects of sampling operations, all of these factors need to be taken into account.
It is caused by the different material compositions at the bottom and top of the tank