Screening-level helpers for caustic mercaptan (Merox-style) extraction units: RS-Na loading in caustic, Kremser-style stage performance, and a disulfide carryback risk score. Use for plant troubleshooting, operator discussion, and order-of-magnitude estimation. Don't use for licensor design (use the licensor's package), for amine treating (use sour-gas-amine-treating), or to predict product disulfide concentration exactly — only the carryback risk direction is reliable.
