K. Liebmann et al., INTEGRATED DESIGN OF A CONVENTIONAL CRUDE-OIL DISTILLATION TOWER USING PINCH ANALYSIS, Chemical engineering research & design, 76(A3), 1998, pp. 335-347
The substantial energy requirement of crude oil distillation columns i
s met partly by costly utilities, such as steam and fuel for fired hea
ters, and partly by heat recovered from the process, using process-to-
process heat exchange. Energy savings, therefore, demand not only a di
stillation column that is energy-efficient, but also a heat exchanger
network (HEN) which minimizes utility costs by maximizing heat recover
y. A new crude oil distillation design procedure is presented which co
nsiders the column, the HEN and their interactions simultaneously, to
minimize utility costs. Pinch analysis is used to determine minimum ut
ility costs prior to the design of the KEN. In this method, the column
is decomposed into a sequence of simple columns, which enables approp
riate distribution of stages and simplifies analysis. Modifications, w
hich further increase the efficiency of the process, are proposed: the
se are the installation of reboilers, rather than stripping steam, and
the thermal coupling of column sections. The detrimental effects of t
hese modifications on the heat recovery opportunities of the process a
re analysed for a distillation tower with side-strippers. A new step-b
y-step design procedure is derived from this analysis, and is applied
to a case study. In the case study, the resulting design offers nearly
20% savings in utility costs over the base case design. The vapour fl
ow in the column is reduced by a similar amount, offering capital savi
ngs, additional flexibility or the opportunity to increase throughput.
The new integrated design procedure considers the column and its asso
ciated HEN simultaneously, aiming to minimize operating costs by obtai
ning the best fit between the process and the available utilities.