Why is the dry point of gasoline lower than the initial boiling point of diesel?

The distillation efficiency of a distillation column is generally expressed in terms of distillation accuracy, which is usually indicated by the composition of two adjacent fractions or the relationship between their distillation curves. If the initial boiling point of the heavier fraction is higher than the final boiling point of the lighter fraction, then it is said that there is a certain \"gap\" between these two fractions; this is also referred to as vacuum separation. The opposite is called “overlap”. Overlap means that some of the light fractions end up in the heavy fractions, or some of the heavy fractions end up in the light fractions. As a result, it not only reduces the yield of light fractions but also affects their quality. Obviously, overlap is caused by poor fractionation accuracy, while depletion indicates higher fractionation accuracy; the larger the gap, the better the fractionation effect.

It simply shows that your fractionation tower performs well; the reason for vacuum formation is mainly due to issues with the analysis method. You can find out more by looking into the differences between Enneberg distillation and true boiling point distillation.

What was said on the first floor is correct; the recovery rates of gasoline and diesel depend not only on the separation efficiency of the distillation tower but also on the operating conditions. The following points are for reference: 1. High reaction temperature results in a high gas phase load, high line speed, and entrainment of mist. 2. Low diesel stripping steam also causes overlap. 3. Excessive reflux at the fractionation top also has an impact. 4. The equipment is under excessive load. In particular, the stripping tower is small, the distillation stop time for diesel is short, and the diameter of the vapor line at the top of the tower is small, preventing the light components from escaping.

Overlap – I agree with what was said above; adjust the operations quickly!

The original poster has clearly explained on the second floor the concept of distillation accuracy and the reasons for overlap. I think what you’re describing is the situation of gaps in fractionation that occur. Why do gaps appear in consecutive components? Where did the middle fraction go? To answer this question, one first needs to understand the two basic concepts of boiling range and boiling point. Boiling range applies to complex mixed components, whereas boiling point applies to pure substances. When complex components are mixed together, with large molecules and small molecules interacting with each other, these complex components will boil at a certain pressure within a specific temperature range. When complex components are separated into simpler ones, the interactions between molecules in the simpler components differ from those among the molecules in the original complex component, resulting in new boiling ranges. And it’s not like what the original poster thought – the boiling range is not like a ribbon; even if it is cut with scissors, its total length remains unchanged. You can imagine, on an extreme level, what would happen if the feed to a fractional distillation tower were separated not into gasoline and diesel, but into individual pure components? The fractions we obtain will no longer have a boiling range, but rather boiling points that jump at intervals. I have already explained why there is a gap; so where does the middle fraction go? My answer is that there is no such thing as an intermediate fraction; once the raw material is separated into gasoline and diesel, the boiling ranges of both the raw material and gasoline/diesel are distinct, and it’s not the case that 2 = 1 + 1.

Well done with the division. . . It’s normal for there to be an Enth equation distillation void in the boiling range. This indicates that the load on the distillation tower is improving. . . . :lol

An empty space indicates good separation efficiency. But the two values should not differ too much, otherwise it will be excessive and result in high energy consumption.