The Hydrocracker is similar to the FCC in that it is a catalytic process that cracks long chain gas oil molecules into smaller molecules that boil in the gasoline, jet fuel and diesel fuel range. The fundamental difference is that cracking reactions take place in an extremely hydrogen rich atmosphere. Two reactions occur. First carbon bonds are broken followed by attachment of hydrogen. Hydrocracker products are sulfur free and saturated.
Function of Hydrocracker
Another difference is operating conditions. Hydro crackers run at high temperature 650-800˚F (345-425˚C) and very high pressures of 1500-3000 psi (105-210 bar). Hydro cracker reactors contain multiple fixed beds of catalyst typically containing palladium, platinum, or nickel. These catalysts are poisoned by sulfur and organic nitrogen, so a high-severity HDS/HDN reactor pretreats feedstock prior to the hydrocracking reactors.
Hydro cracker units may be configured in single stage or two stage reactor systems that enable a higher conversion of gas oil into lower boiling point material.
Typical feed stock to a Hydrocracker includes FCC cycle oil, coker gas oil and gas oil from crude distillation. Heavy naphtha from the Hydrocracker makes excellent Catalytic Reformer feedstock. Distillates from Hydrocracking make excellent jet fuel blend stocks. Light ends are highly saturated and a good source of iso-butane for alkylation.
The yield across a Hydro cracker may exhibit volumetric gains as high as 20-25% making it a substantial contributor to refinery profitability. You can check the SRU from this source
|
VHC
|
VGO
Hydeocraking Unit |
Yields
|
|
Feed
|
VGO
|
0.97
|
|
Hydrogen
|
0.03
|
|
|
Total
|
1
|
|
|
Products
|
LPG
|
0.05
|
|
VHC
Naphta |
0.39
|
|
|
VHC
Gasoil |
0.44
|
|
|
Unconverted
Oil |
0.07
|
|
|
Loss
|
0.05
|
|
|
Total
|
1
|