Refinery Yield Calculator

A delayed coker exists specifically to process the leftover residuum, converting 60% of it into lighter, more valuable products (25% into gasoline, 15% into diesel) and coking off another 25% as solid petroleum coke. That only leaves 40% of the original residuum pool as residual fuel oil, which is why toggling the coker on visibly shrinks the residual output and adds a Pet Coke line.

Each base distillation cut — light naphtha, heavy naphtha, kerosene, diesel, and vacuum gas oil — is defined by a formula that scales with °API; light and heavy naphtha yields increase with higher (lighter) API gravity, while vacuum gas oil's base yield actually decreases slightly. This reflects the real-world pattern that lighter crudes distill into a larger share of light, valuable products even before any cracking or coking happens.

Both units draw from the same base vacuum gas oil (VGO) pool independently in this model — the FCC converts about half of it to gasoline, and the hydrocracker converts about 60% of it to diesel — so enabling both adds their effects together before the whole product slate is renormalized to 100%. A real refinery's two units would typically compete for the same physical VGO feed rather than each drawing from the full amount, so treat combined-unit scenarios as more directional than a single-unit scenario.

After summing all base yields and conversion-unit effects, the calculator divides every product stream by the raw total and multiplies by 100 — a normalization step that guarantees the reported percentages always sum to 100% regardless of the underlying assumptions. This keeps the output looking like a complete mass balance, though it means any imprecision in the individual yield formulas gets spread proportionally across all products rather than showing up as a shortfall.