The relationship between gasoline dry point and diesel acidity
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Our plant’s atmospheric and vacuum distillation units process the Jinzhou 9-3 crude oil; the acidity level of the refined product remains at 0. However, as required by management, the dry point of the gasoline has been increased. For the refined diesel, after treatment via alkali washing, water washing, and sedimentation, the acidity level rises, reaching up to 14 in some cases, and there is also the issue of alkaline residue. What is the relationship between these phenomena, and how can it be resolved? handshake
Acidic components in petroleum are present in small amounts in the fractions before 220; a considerable portion of them is found in diesel. When the dry point of gasoline is increased and its yield is enhanced, the yield of diesel inevitably decreases. As a result, the acidity of the acidic components in diesel rises due to the reduced amount of diesel. Therefore, in diesel refining, it is necessary to increase the concentration or flow rate of the alkaline solution. The alkaline washing method for diesel refining has specific requirements regarding the acidity of the diesel; diesel with low acidity can be easily purified, while diesel with high acidity makes the process more difficult to handle, as it exceeds the limitations of this purification method. In such cases, not only is the acidity not removed thoroughly, but the diesel also tends to emulsify or contain residues, which represents a challenge in oil refining. Solutions can be explored by adjusting factors such as temperature, mixing intensity, and alkali concentration, or by using diesel demulsifiers.