Plant−Model Mismatch Analysis in Deethyleniser Simulation. 1. Methodology

Abstract

Confidence in the accuracy of a simulation model and by implication the thermodynamic data model(s) used, particularly for separation equipment such as a deethyleniser, requires validation against actual plant operating data. A methodology has been developed that quantifies plant−model mismatch with a Calculator module appended to a PRO/II (Simulation Sciences, Inc.) Column module to facilitate an assessment of the relative accuracy of alternative simulation model formulations. The methodology is based on a manual stepwise optimization procedure using a preferred formulation of the simulation model with the key adjustable modeling parameter defined as the effective average equilibrium tray efficiency . The methodology seeks to minimize an Error Objective Function that calculates the sum of the weighted and variance-normalized least-squares errors around the deethyleniser involving as many plant measurements as practical taking into account the wide range of accuracy inherent in the various measurements.