(426e) Dynamic Simulation for Safety Analysis in An Integrated Front-End De-Propanizer System of An Ethylene Plant

Process simulation provides many applications in the Chemical Process Industry (CPI), mostly by steady-state (SS) one in process design. Recently, dynamic simulation has caught more attention in its contributions in operations such as plant startup, shutdown and maintenance, process upsets and operator training system. A general methodology in development, validation and application of a CPI process dynamic simulation in a situation of plant upset is presented. Various levels of simplifications and complexity are attempted to determine an optimal fit to model’s application purpose. Process upsets are simulated once the model gains a certain level of reliability. Model responses are collected and evaluated in order to generate milestones and guidance to real-life practice. Unexpected behaviors at certain equipment can be identified and reduced/prevented to guarantee efficient and safe operation.

In this paper, dynamic model of the integrated Front-end De-Propanizer system (including the 4^th-Stage charged gas compressor, High-pressure and Low-pressure De-Propanizer columns, Acetylene converter, and other units) in an Ethylene plant is generated following the introduced methodology. There are four stages: simplified SS simulation, elaborated SS model, dynamic model, and process upset simulation. Data analysis (from both design and historian) and literature survey are conducted to achieve model input specifications. The system’s reactions to plant upsets are demonstrated by the dynamic model. Thorough observations are paid to the hydrogenation reactor of Acetylene and MAPD (Methyl-Acetylene and Propadiene) in three catalytic reactors in series and two distillation columns to avoid thermal runaway and over-pressurized system while keeping product streams and other units in-specs. Three different approaches of modeling the Acetylene converter are carried out to identify each suitable one to specific scenario or purpose. Process disturbances are automated in the simulation model and temperature control schematics of the Acetylene reactor are studied.