Steam Cracker Co-Processing Mass Balance Basics
Co-processing plastic pyrolysis oil in steam crackers requires yield-based mass balance attribution under ISCC PLUS rules to substantiate circular claims.
Radiant Coil Coking
Meaning
Carbon deposition on the inner walls of high-temperature furnace tubes reduces heat transfer efficiency during thermal cracking. In the manufacturing of olefin feedstocks, radiant coil coking describes the gradual buildup of coke that occurs inside the ethylene production reactor. This layer insulates the process gas from the heat source and forces the plant to increase furnace temperatures.
Production lines must be shut down periodically to burn off these carbon deposits.
Thermal Deposition
High temperatures required to crack naphtha or gas feeds inevitably trigger secondary reactions that form heavy carbonaceous solids. This radiant coil coking limits the continuous runtime of the furnace, typically restricting runs to several weeks or months. Plant operators use steam injection to mitigate the rate of deposit formation.
Supply Disruption
Furnace decoking requires offline thermal and mechanical cleaning cycles that temporarily reduce the output of the monomer plant.
Polymer Pricing
Fluctuations in monomer availability caused by decoking schedules directly impact the supply of downstream polymer resins. When radiant coil coking reduces the operating rate of major ethylene crackers, resin producers experience monomer shortages and must limit their output of polyethylene. These supply constraints trigger rapid price increases for virgin plastics in the polymer sourcing market.
Moulders using these resins face rising raw material costs and must manage their inventories carefully to avoid production stops.