BOTTOM STRIPPING
To determine the amount of liquid to be vaporized by the stripping
steam in the bottom of the tower, it is necessary to construct the flash
curve of this liquid (called the initial bottoms). The flash curve of the
reduced crude can be constructed from the flash curve of the whole
crude.9 It is assumed that the initial bottom is flashed in the presence of
stripping steam at the pressure existing on top of the stripping plate and at
the exit temperature of liquid from this plate.
Approximately 50-60% of the crude is vaporized in the flash zone of
the atmospheric tower. The unvaporized crude travels down the stripping
section of the tower, containing four to six plates, and is stripped of any
remaining low-boiling distillates by superheated steam at 6000F. The
steam rate used is approximately 5-101b/bbl of stripped product. The
flash point of the stripped product can be adjusted by varying stripping
steam rate.
SIDESTREAM STRIPPER
Distillate products (kerosene and diesel) are withdrawn from the column
as sidestream and usually contain material from adjacent cuts. Thus, the
kerosene cut may contain some naphtha and the light diesel cut may contain
some kerosene-range boiling material. These side cuts are steam stripped
using superheated steam, in small sidestream stripper columns, containing
four to six plates, where lower-boiling hydrocarbons are stripped out
and the flash point of the product adjusted to the requirements.
To determine the amount of liquid to be vaporized by the stripping
steam in the bottom of the tower, it is necessary to construct the flash
curve of this liquid (called the initial bottoms). The flash curve of the
reduced crude can be constructed from the flash curve of the whole
crude.9 It is assumed that the initial bottom is flashed in the presence of
stripping steam at the pressure existing on top of the stripping plate and at
the exit temperature of liquid from this plate.
Approximately 50-60% of the crude is vaporized in the flash zone of
the atmospheric tower. The unvaporized crude travels down the stripping
section of the tower, containing four to six plates, and is stripped of any
remaining low-boiling distillates by superheated steam at 6000F. The
steam rate used is approximately 5-101b/bbl of stripped product. The
flash point of the stripped product can be adjusted by varying stripping
steam rate.
SIDESTREAM STRIPPER
Distillate products (kerosene and diesel) are withdrawn from the column
as sidestream and usually contain material from adjacent cuts. Thus, the
kerosene cut may contain some naphtha and the light diesel cut may contain
some kerosene-range boiling material. These side cuts are steam stripped
using superheated steam, in small sidestream stripper columns, containing
four to six plates, where lower-boiling hydrocarbons are stripped out
and the flash point of the product adjusted to the requirements.
