From the results obtained in this work we can make the following statements. The closeness of separa-
tion with distillations in accordance with GOST 2177-66 meets the requirements of the refinery; however,
the TBP distillation data indicate a considerable overlap of adjacent cuts (see Table 1). For example, the
kerosine cut contains 20.5% fraction distilling below 180~ and the content of kerosene fractions dwelling
below 220~ in the diesel fuel cut is more than 10%.
The significant content of fractions distilling below 180~ in the kerosine cut is partly explained by the
fact that no steam is fed to the stripping section. If closer fractionation of the kerosine is necessary, it will
be desirable to provide the stripping tower with a reboiler, using the waste heat from the diesel fuel or residue
streams, or high-pressure steam.
The hydrodynamic calculations show that in the naphtha and kerosine sections the trays are operating
with vapor velocities considerably below the allowable limits. Such operating conditions are particularly un-
favorable for trays of this type, since the entire stream of liquid moves over the S-shaped elements, and an
excessive decrease in vapor velocity may be the source of liquid weeping and lower tray efficiency. In this
connection, attention is drawn to the rather nonuniform distribution of vapor and liquid loads through the in-
dividual sections of the tower. For optimization of the process regime, a design calculation study was made
on the atmospheric tower, with the aim of a more uniform distribution of loads and closeness of distillate
separation throughout the entire operating height of the tower.
As input data we used the indices of the process regime obtained in the operating test on the unit; as the
basis for the distribution of the reflux heat between PTsO-1 and PtSO-2 we used the operating indices of a
unit, of similar type and capacity, at the Kirishi refinery, the operation of which gives a closer separation of
distillate fractions without any additional intermediate circulating reflux. The withdrawal of heat in this unit
is accomplished by PTsO-1, 2, as specified in the typical unit design.
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