Question regarding the factors affecting the dry point of naphtha in the overhead reflux tank of the hydrocracking fractionation tower?
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Regarding the dry point of naphtha, the top temperature has a significant impact on it; it is proportional to temperature and inversely proportional to pressure. The properties of the feed oil also play a role in this regard. If the properties of the feed oil become lighter, with all other operating parameters remaining unchanged, what changes will occur in the dry point of naphtha? Will it get heavier or lighter? I need experts to give me some advice!
With the top temperature and pressure remaining constant, as the properties of the feedstock become lighter, the dry point of the naphtha will increase.
Under normal operation, if the properties of the feedstock become lighter, the pressure at the top of the tower will increase. If the temperature at the top of the tower is kept constant in such a situation, the dry point of the naphtha will become lower; usually, the dry point is maintained by increasing the temperature at the top of the tower. If the pressure at the top of the control tower is kept constant artificially, the dry point of naphtha will still rise. I have experienced similar situations: in a butane removal tower, the naphtha fed into the system absorbed too many components with carbon numbers below 4, which resulted in lighter feed components. Automatic control was applied to the pressure and temperature at the top of the tower; as a result, the levels of components with carbon numbers above 5 in the liquefied gas at the tower top exceeded the allowed limits significantly.
This post was last edited by hlcl on 2016-9-11 at 13:49. My understanding is that with constant pressure and temperature, an increase in the light components reduces the vapor pressure of the heavy components, which necessarily leads to more vaporization of the heavier components. Just like blowing steam at the bottom of the tower to reduce the partial pressure of oil and gas. Therefore, the pressure needs to be increased to suppress the vaporization of the Reorganization components. However, due to the higher relative volatility of the light components, as pressure increases, the vapor pressure of the heavy components also rises. If temperature is not taken into account, the amount of heavy components will decrease and the boiling point will drop; therefore, it is necessary to increase the temperature appropriately to promote the vaporization of the heavy components.
Well, it’s about reducing the partial pressure of the heavy components, which could end up in the light components! Got it, thanks