Operational Stabilization of Industrial Trichlorosilane Rectification: A Composite Stability Index Framework

Trichlorosilane (TCS) rectification establishes the purity foundation for downstream polysilicon production used in photovoltaic and semiconductor manufacturing. Operational stability at the column level depends on how reflux flow, temperature distribution across trays, and the occurrence of off-spec fractions are managed across continuous shift operation. Many production facilities, particularly Central and Eastern European and post-Soviet sites that remain part of the global chlorosilane feedstock base, operate with legacy instrumentation that limits real-time analytics. A composite shift-level operational metric, the Trichlorosilane Rectification Stability Index (TRSI), is introduced. Three normalized components form the composite: reflux deviation, tray temperature gradient variance, and off-spec fraction yield. Calibration proceeds through retrospective reconstruction of operational case data drawn from an organochlorosilane production facility active between 2001 and 2009. Three response bands, Stable, Watch, and Intervene, are defined and linked to a graduated set of shift-master actions. Sensitivity analysis across alternative weight configurations indicates that band membership remains directionally stable under reasonable perturbations of the component weights. Application of the framework appears to support earlier recognition of compound disturbance patterns at facilities where shift-level decisions rely on intermittent compositional readings. Limitations of a retrospective single-site design are acknowledged, and directions for multi-plant validation are outlined.