Environmental Engineering Reference
In-Depth Information
3.4.1.1 Unibon Process
Typically, this process has been used downstream of the deasphalting unit. It may also be used
for hydroprocessing of either VGOs and HGOs or the blend of VGO with DAO. Depending on
the feed, the process can be used as a single stage or two-stage configuration. For example, the
commercial configuration of the Unibon process is using DAO as the feed consisted of two
single fixed reactors: one operating predominantly in HDM mode (guard reactor) and the other
in the HDS mode [128,129] . The DAO feed contained about 27 ppm of V+Ni and less than
1% of asphaltenes. The blend of VGO and DAO can also be used. To suit refinery
requirements, different configurations of the Unibon process, i.e., BOC Unibon, RCD Unibon,
etc., have been licensed [130] . For example, the Unicracking, the residue desulfurization
(RDS) version of the Unibon process, shown in Fig. 3.11 , was designed primarily for the HDS
of ARs and VRs derived from the conventional crudes [131] .In Fig. 3.12 , besides guard
reactor and two HDS reactors, all necessary downstream and upstream units are shown as
well. Most of these units are common for other similar commercial systems employing fixed
bed reactors. During dewaxing of VGO and DAO to produce lube base oil, HIS and HCR are
important functionalities besides other hydroprocessing reactions. This can only be achieved
using several types of catalysts. For this purpose, the modified Unibon process, such as
Unicracking process ( Fig. 3.11 ), comprising two reactor vessels with several sections in each,
has been used.
A number of other commercial processes employing fixed bed reactors have been licensed. For
example, the asphaltenic bottom conversion (ABC) process developed in Japan has similar
features as the Unibon process [130] . A modified version of this process includes the recycling
of asphalt from the deasphalting unit to the HDM reactor for further processing, i.e., recycle to
Figure 3.12: Simplified flowsheet of Unibon process [From ref. 130 . Reprinted with permission].
 
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