I’m not sure if this is correct regarding beginners’ cognition; I’d like to ask for your advice
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The last edit to this post was made by Refiner on 2018-3-8 at 09:21. Firstly, the distillation tower is used primarily to control the dry point of gasoline, as well as the freezing point and flash point of diesel. The freezing point of gasoline is determined by the temperature at the top of the tower; a higher temperature at the top results in more light components in the gasoline, thereby lowering its dry point. The diesel dew point is controlled by the distillation temperature; a higher distillation temperature results in more light components reaching the top of the tower, while the heavier diesel components remain below, leading to a higher dew point. The flash point is controlled by the stripping steam. The reprocessing oil tank is controlled by the reaction temperature and reaction depth; it can also be slightly regulated by returning the reprocessed oil to the tower. Stable control of gasoline vapor pressure: a higher bottom temperature results in more heavy components in the gasoline, thus a lower vapor pressure. Taking the absorption tower as an example, if the temperature at the top of the tower is too high, the absorption efficiency is poor. A high temperature at the top results in an increased amount of Reorganization components, and these components tend to be present in the dry gas as C3 compounds. At too low a temperature, the absorption efficiency is good; therefore, there should be less liquefied gas in the dry gas. But the director said it’s not necessarily the case – I don’t know why ? ? It’s a bit messy. . . . .
Nothing is that absolute; there are too many factors at play in actual production. Even when the problem is the same, different approaches to analysis can lead to different conclusions. If the analysis is roughly similar, it refers to the dry point of gasoline, not its freezing point – must have made a mistake
Generally, this is indeed the correct way to control it
A high distillation top temperature increases the dry point of gasoline.
It seems you’re really a beginner; what you wrote above is incorrect, and it’s likely to confuse even your supervisor. I’ll just mention two points. 1. “The gasoline dew point is controlled by the tower top temperature; a higher tower top temperature results in more light components in the gasoline, thereby lowering the dry point.” ”The gasoline dew point seems to be incorrect; it should be: The dry point of gasoline is controlled by the tower top temperature, and as the tower top temperature increases, so does the dry point of gasoline ； “Gasoline contains more light components, which lowers its dry point. ”This statement is incorrect; the amount of light components in gasoline has little to do with its dry point, as the dry point is determined only by the heaviest components present in gasoline. It can only be said that for gasoline with similar compositions, those with a higher proportion of light components may have a lower flash point than those with a lower proportion of light components. 2. “Stabilizing the vapor pressure of gasoline: a higher bottom temperature results in more heavy components in the gasoline, thereby yielding a lower vapor pressure.” ”There is a concept of controlling the vapor pressure of the stabilized gasoline produced at the bottom of the stabilizer, but it isn’t explained in sufficient detail. Firstly, the stabilizer tower is a roughing tower; the light components produced at the top of this tower are liquefied gas – a name that doesn’t sound like that of a proper product. These components are mainly composed of C3 and C4 hydrocarbons. The stabilized gasoline obtained at the bottom of the tower has a more diverse composition, being primarily made up of C5 and C11 hydrocarbons, with a small amount (around 4%) of C4 present as well. This C4 content is crucial for controlling the vapor pressure of gasoline; it is what we generally refer to as a key component. In stabilized gasoline, C4 is the key light component at the bottom of the tower, while in liquefied gas, C5 is the key heavy component at the top. Since the vapor pressure of C4 is much higher than that of C5, it is C4 that plays a key role in determining the vapor pressure of gasoline; the level of vapor pressure serves as an indicator of the content of light components in gasoline. It can be said that a high temperature at the bottom of the tower, along with a high proportion of heavy components in the gasoline, results in fewer light components; it is this lack of light components that leads to a low vapor pressure of the gasoline. Under normal circumstances, during storage, C4 may evaporate first in gasoline with high vapor pressure, resulting in oil loss. However, in winter, gasoline with high vapor pressure or a high C4 content has a lower initial boiling point, which facilitates ignition in low ambient temperatures; this is similar to the process of producing -20# light diesel through distillation in winter.
Everything you said here is incorrect; please add information regarding the 5th floor. The main functions of returning the material to the distillation tower are outlined in the handbook； There is a cooler at the compressor outlet; additional two-stage cooling is required before mixing with the desorbed gas ； The poor absorption efficiency in the absorber and the high temperature at the top of the tower are not the main factors; crude gasoline and supplementary absorbent are also involved. The dry gas exits from the top of the reabsorber, where oil from the middle stage of distillation is used as an absorbent.