In the process of crude oil distillation under atmospheric and vacuum pressure, naphthenic acid with different relative molecular mass is vaporized, condensed and condensed with the fraction close to its boiling point, and dissolved in the fraction, so that the fraction has corrosive effect on equipment. The corrosion performance of naphthenic acid is related to molecular weight, and low molecular naphthenic acid is more corrosive.

It is generally believed that the corrosion mechanism of naphthenic acid on equipment is as follows: naphthenic acid activity is more active in liquid phase near boiling point. Therefore, the corrosion Z is serious at the junction of vapor-liquid phase, and it is not corrosive below 220 ℃. With the rise of temperature and gradually increase, usually in 270-280℃Z, more than 280℃, naphthenic acid partial gasification, but not condensation, and the liquid concentration of naphthenic acid is low, so the corrosion decreases. When the temperature is above 350℃, the gasification speed of naphthenic acid is accelerated, the gas phase speed is increased, and the corrosion rate rises rapidly again, but most of it is due to the effect of sulfur, and the corrosion phenomenon does not appear above 400 ℃.

According to the information, the naphthenic acid may have been basically all vaporized above 400℃, and the high-temperature parts of the equipment are no longer corroded. That is, with the increase of temperature in the high temperature region, there are two corrosion peaks of naphthenic acid corrosion (270-280 degrees and 350-400 degrees).

In the process of crude oil distillation under atmospheric and vacuum pressure, naphthenic acid with different relative molecular weight with isoctanoic acid, paint drying agent, degreased naphthenic acid and its boiling point similar fraction of vaporization, condensation and condensation, and dissolved in the fraction, so that the fraction has corrosive effect on equipment. The corrosion performance of naphthenic acid is related to molecular weight, and low molecular naphthenic acid is more corrosive.

It is generally believed that the corrosion mechanism of naphthenic acid on equipment is as follows: naphthenic acid activity is more active in liquid phase near boiling point. Therefore, the corrosion Z is serious at the junction of vapor-liquid phase, and it is not corrosive below 220 ℃. With the rise of temperature and gradually increase, usually in 270-280℃Z, more than 280℃, naphthenic acid partial gasification, but not condensation, and the liquid concentration of naphthenic acid is low, so the corrosion decreases. When the temperature is above 350℃, the gasification speed of naphthenic acid is accelerated, the gas phase speed is increased, and the corrosion rate rises rapidly again, but most of it is due to the effect of sulfur, and the corrosion phenomenon does not appear above 400 ℃.

According to the information, the naphthenic acid may have been basically all vaporized above 400℃, and the high-temperature parts of the equipment are no longer corroded. That is, with the increase of temperature in the high temperature region, there are two corrosion peaks of naphthenic acid corrosion (270-280 degrees and 350-400 degrees).