PTQ Q2 2025 Issue

LPG (optionally to s team c racking )

Gas processing

Naphtha to s team c racker

Transportation fuels pool

Light naphtha

Isomerisate

Isomerisation

Chemicals pool

Heavy naphtha

Reformate

CRU

BTX

BTX recovery

CDU Atmospheric

Jet fuel

Diesel

HC naphtha

HC gasoline

Pyrolysis oil

HC diesel

Atmospheric g asoil

Iso-C

Alkylate

Propylene

Alkylation

Light vacuum

g asoil

=C, =C

CDU Vacuum

FCC gasoline

FCC

Heavy vacuum gasoil

FCC gasoline

Fuel oil

Coker naphtha

Naphtha to hydrotreating (optionally to steam cracking)

DCU

Coker gasoil

Vacuum residue

Petroleum coke

HT - Hydrotreater

HC - Hydrocracker

DCU - Delayed

CDU - Crude

CRU - Catalytic

FCC - Fluid catalytic cracking

Pyrolysis oil injection points

coking unit

distillation unit

reforming unit

Figure 1 High complexity refinery flow diagram

pyoil by reducing halogens to acceptable levels upstream of FCC units. Addressing high levels of alkali metals in the pyoil is a lot more difficult using purely adsorption technology, even though certain experimental success has been achieved. If the content of alkali metals in the FCC feedstock becomes unmanageable through blending or modifications of FCC catalyst formulation, a dedicated hydroprocessing unit to remove metals in the HDM reactor is among plausible yet capital-intensive solutions. Delayed coking unit (DCU) Delayed coking is a basic bottom-of-the-barrel conversion process that transforms heavy residues from vacuum distil- lation into coke and a range of liquids such as LPG, naphtha, gasoline, and gasoils. The major advantage of DCU technol - ogy is that it handles the most difficult-to-process bottoms, essentially squeezing valuable lighter liquids from low-value streams. Capable of processing tars, bitumens, and FCC slurry oils, DCU is critical for deep crude oil conversion. There is at least some experience in the industry with blending pyoils into DCU feeds. In addition, there are reports on the potential feasibility of dosing actual waste plastic into DCU, omitting the pyrolysis step, although there is no evidence of commercial use.15 The advantage that DCU brings is almost complete metals rejection in the coke drums, which is a major benefit if the bottoms of pyoils were to be processed. Nevertheless, sim - ilar to FCC, most product streams of DCU, after necessary

post-processing steps, are directed to the fuel pool. Naphtha yields are generally low at about 8-15%, and since the heav - iest bottoms are used as the feed DCU, naphtha is typically very rich in sulphur, requiring further hydrotreatment. While using DCU as a primary conversion route for pyoils into cycled chemicals requires further assessment, it defi - nitely could play its role in the short- to mid-term, processing the heaviest pyoil bottoms or high metals sludges, which are not possible to process using other established technologies. Upgrading needs (DCU) There is no limit to purity requirements imposed on plas - tic-based pyoils as feedstock to DCU units. Most commercial feeds directed to DCU are much heavier than typical pyoils, with impurities content in some of the bitumen and FCC slur- ries substantially exceeding those found in most pyoils. In this regard, DCU is not seen as the core processing asset for pyoils and instead could play only an auxiliary role to process heavy waxes or those that are not possible to convert into higher value products in an economically feasible fashion. Crude distillation unit (CDU) The CDU is the heart of a classical refinery. The CDU distils the crude into LPG, naphtha, kerosene, gasoil, and heavy bottoms, which are then processed in various downstream units to higher value products. Even though the CDU is not the asset that comes to mind when discussing circularity value chains in plastics, there is merit in bringing it up. As previously mentioned, there will be a certain adoption

PTQ Q2 2025