ISO 22095 Mass Balance Chain of Custody Audit Requirements
ISO 22095 mass balance audits demand strict site boundaries, verified baseline yield conversions, and zero negative credit balances across accounting periods.
Co-Processing Steam Cracker
Meaning
Petrochemical units process mixed fossil and recycled hydrocarbon feeds simultaneously to produce base olefins. Operating a co-processing steam cracker introduces pyrolysed plastic oils or bio-based naphtha directly into thermal cracking coils alongside conventional straight-run naphtha. The thermal reaction yields ethylene and propylene streams that match the physical properties of purely fossil outputs.
It governs feed composition ratios and cracking severity parameters, stopping at the boundary where liquid pyrolysis oil contaminants cause tube coking or catalyst poisoning in downstream units.
Yield Alteration
Cracking behavior shifts when alternative feedstocks enter thermal furnaces. Pyrolysis oils derived from mixed post-consumer waste contain higher levels of conjugated diolefins and organic halides than standard fossil feedstocks. Adjusting coil outlet temperatures compensates for feed variability to maintain target ethylene yields.
Contaminant Limit
Trace metals and silicon compounds in recycled oil shorten furnace tube operational cycles. Pretreatment hydrotreating removes chlorine and nitrogen species before cracking. Maintaining severe feedstock purity standards protects internal metallurgy from catastrophic high-temperature corrosion.
Mass Allocation
Mass balance accounting assigns recycled content fractions to outgoing chemical streams. Because physical molecules of recycled and virgin origins mix completely inside the furnace, certified attribution protocols track carbon units through cracking and polymerisation. Verification systems audit mass allocation to substantiate environmental performance claims for polyolefin resins.