527
Catalytic Cracking
19.4.7 sHell FCC ProCess
The Shell FCC process is designed to maximize the production of distillates from residua (Table 19.8).
In the process, the preheated feedstock (vacuum gas oil, atmospheric residuum) is mixed with
the hot regenerated catalyst. After reaction in a riser, volatile materials and catalyst are separated
after which the spent catalyst is immediately stripped of entrained and adsorbed hydrocarbons
in a very effective multistage stripper. The stripped catalyst gravitates through a short standpipe
into a single vessel, simple, reliable and yet efficient catalyst regenerator. Regenerative flue gas
passes via a cyclone/swirl tube combination to a power recovery turbine. From the expander turbine, the heat in the flue gas is further recovered in a waste heat boiler. Depending on the environmental conservation requirements, a deNO x ing, deSO x ing, and particulate emission control
device can be included in the flue gas train.
Feedstock pretreatment of bitumen (by hydrogenation) prior to fluid catalytic cracking (or for
that matter any catalytic cracking process) can result in enhanced yield of naphtha. It is suggested
that mild hydrotreating be carried out upstream of a fluid catalytic cracking unit to provide an
increase in yield and quality of distillate products. This is in keeping with earlier work where mild
TABLE 19.8
Feedstock and Product Data for the Shell FCC Process
Feedstock
Residuum a
Residuum a
API
18.2
13.4
Sulfur, wt.%
1.1
1.3
Carbon residue, % w/w.
1.2
4.7
Products
Gasoline C5-221°C, C5-430°F, wt.%
49.5
46.2
Light cycle oil (221°C–370°C, 430°F–700°F), wt.%
20.1
19.1
Heavy cycle oil (>370°C, >700°F), wt.%
5.9
10.8
Coke, wt.%
5.9
7.6
a Unspecified.
TABLE 19.7
Feedstock and Product Data for the RCC Process
Feedstock
Residuum a
Residuum a
Residuum a
API
22.8
21.3
19.2
Sulfur, wt.%
Nitrogen, wt.%
Carbon residue,% w/w
0.2
6.4
5.5
Nickel, ppm
1.0
22.0
34.0
Vanadium, ppm
Products
Gasoline (C5-221°C, C5-430°F), vol.%
59.1
56.6
55.6
Light cycle oil (221°C–322°C, 430°F–610°F), vol.%
16.3
15.4
16.3
Gas oil (>322°C, >610°F), vol.%
6.2
9.0
9.6
Coke, wt.%
8.4
9.1
10.8
a Unspecified.
Catalytic Cracking
19.4.7 sHell FCC ProCess
The Shell FCC process is designed to maximize the production of distillates from residua (Table 19.8).
In the process, the preheated feedstock (vacuum gas oil, atmospheric residuum) is mixed with
the hot regenerated catalyst. After reaction in a riser, volatile materials and catalyst are separated
after which the spent catalyst is immediately stripped of entrained and adsorbed hydrocarbons
in a very effective multistage stripper. The stripped catalyst gravitates through a short standpipe
into a single vessel, simple, reliable and yet efficient catalyst regenerator. Regenerative flue gas
passes via a cyclone/swirl tube combination to a power recovery turbine. From the expander turbine, the heat in the flue gas is further recovered in a waste heat boiler. Depending on the environmental conservation requirements, a deNO x ing, deSO x ing, and particulate emission control
device can be included in the flue gas train.
Feedstock pretreatment of bitumen (by hydrogenation) prior to fluid catalytic cracking (or for
that matter any catalytic cracking process) can result in enhanced yield of naphtha. It is suggested
that mild hydrotreating be carried out upstream of a fluid catalytic cracking unit to provide an
increase in yield and quality of distillate products. This is in keeping with earlier work where mild
TABLE 19.8
Feedstock and Product Data for the Shell FCC Process
Feedstock
Residuum a
Residuum a
API
18.2
13.4
Sulfur, wt.%
1.1
1.3
Carbon residue, % w/w.
1.2
4.7
Products
Gasoline C5-221°C, C5-430°F, wt.%
49.5
46.2
Light cycle oil (221°C–370°C, 430°F–700°F), wt.%
20.1
19.1
Heavy cycle oil (>370°C, >700°F), wt.%
5.9
10.8
Coke, wt.%
5.9
7.6
a Unspecified.
TABLE 19.7
Feedstock and Product Data for the RCC Process
Feedstock
Residuum a
Residuum a
Residuum a
API
22.8
21.3
19.2
Sulfur, wt.%
Nitrogen, wt.%
Carbon residue,% w/w
0.2
6.4
5.5
Nickel, ppm
1.0
22.0
34.0
Vanadium, ppm
Products
Gasoline (C5-221°C, C5-430°F), vol.%
59.1
56.6
55.6
Light cycle oil (221°C–322°C, 430°F–610°F), vol.%
16.3
15.4
16.3
Gas oil (>322°C, >610°F), vol.%
6.2
9.0
9.6
Coke, wt.%
8.4
9.1
10.8
a Unspecified.