Environmental Engineering Reference
In-Depth Information
Table 6.12: Results of density grading of NiMo/Al 2 O 3 catalyst [From ref. 465 . Reprinted with
permission].
RVA a (%)
Catalyst
Yield (wt.%)
Compacted bulk
density (lbs/cu ft)
Surface area
(m 2 /g)
Vanadium
(wt.%)
Fresh
-
36
330
0
100
Composite
-
53
232
9 . 0
74
Light
28
44
293
4 . 7
84
Med-light
36
48
269
7 . 2
76
Med-heavy
16
52
233
10 . 0
69
Heavy
20
66
125
14 . 7
51
a
Relative volume activity (hydrodesulfurization [HDS]) compared with fresh catalyst.
6.4.4 Commercial Regeneration Processes
A brief description of the best-known commercial regeneration processes as well as the
emerging processes is the intention of this section. Thus, this is by no means an exhaustive
review of the regeneration processes. There might be other processes operating on a
commercial scale and/or near commercial scale, although their details are not available in an
open literature. Apparently, some companies are reluctant to provide even brief information on
their process. Therefore, a more detailed account of the industrial regeneration processes
cannot be given.
6.4.4.1 Belt Regeneration Process
This process has been operated by Porocel (previously CRI). The schematics of the belt
regeneration process are shown in Fig. 6.38 [467] . The process comprises of the de-oiling and
regeneration sections. The former has a provision for sieving the spent catalyst to remove
fines. The heat required for this step is supplied by the combustion of a fuel gas. The details of
the process such as radiant tube burner, bed thermocouple and gas flow are shown in Fig. 6.39
[468] . To achieve an efficient oil removal, the entrance temperature of de-oiling section is
maintained at 150-300 C, whereas the exit at 300-330 C.
The regeneration section of the belt regeneration process consists of a rectangular, stationary
tunnel furnace, about 3m high, 3m wide, and almost 25m long. A fine mesh stainless steel
belt can continuously move inside of the vessel. The regeneration section is divided into four
distinct zones. Each zone has a number of inlets for oxidation medium located above and
below the belt. The spent catalyst is placed on the moving belt at a bed depth varying from 0.5
to 5 cm. As the catalyst moves through each zone, it is subjected to different O 2 concentrations
and different temperatures. Usually, in the last zone of regeneration section, the catalyst is
contacted with air. The heat to regeneration section is provided by the combustion of fuel gas
 
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