Ethylene - Ethane Splitter Optimization Control Program

Optimized operation of the Ethylene - Ethane Splitter column is critical to ensure ethylene product purity and minimize ethylene slippage in the column bottoms stream, while still utilizing the maximum separation and hydraulic processing capacity of the column. Often, the prevalent advance process control schemes do not take into account real time variation in column hydraulics due to changing plant operating conditions like feed composition, feed flow rate, etc. and the corresponding scope available in the column’s feed processing capacity. Process optimization without accounting for such critical factors leads to column operation below its maximum processing capacity and/or the column experiences disturbances with operational variations. This paper focusses on a control program designed to optimize Ethylene - Ethane Splitter operation, while taking into account all possible variations in plant operating parameters.

Actual plant data, simulation model and column tray hydraulic model results are considered to generate the empirical correlations that are used in the program to estimate the Ethylene - Ethane Splitter feed condition, reflux and reboiling requirements and corresponding column hydraulic loads and flooding numbers. Based on these details, the column operating parameters are adjusted/optimized within the operational boundary limits by the control program, based on the prevailing needs. At higher feed rates, flooding is avoided by relaxing ethylene slippage, whereas at lower feed rates, ethylene recovery is maximized based on condenser, reboiler and column hydraulic limitations.