CC-97-139 PLANT WIDE CLOSED LOOP REAL TIME OPTIMIZA TION AND ADVANCED CONTROL OF ETHYLENE PLANT - CLRTO IMPROVES PLANT PROFITABILITY & OPERABILITY

Description:

Increasing plant profitability and improving plant operability are the primary objectives of advanced control and closed loop real time optimization. Mobil Chemical’s Beaumont olefins plant has implemented an advanced multi variable control and plant wide closed loop real time optimization technology for its ethylene plant. The overall system includes model based control of pyrolysis furnaces and multi variable constraint control for compressors and major separation towers. A furnace feed allocation supervisory control system which responds to constraint signals from heaters and downstream multi variable controllers for compressors and towers provides feed maximization subject to downstream constraints. The real time optimization system is based on a detailed rigorous engineering representation of a plant in a residual form (open form)model. It is capable of sending targets for up to 48 optimized variables to the underlying control system. The overall system detects if the plant is steady, collects and validates process measurement data, calculates performance parameters, solves the optimization problem, and then automatically implements the optimized targets. The main objective of this paper is to describe the overall system with an emphasis on the important effects of Closed Loop Real Time Optimization (CLRTO) on plant operability and profitability. The CLRTO project was completed in IQ 94, the system has been in continuous operation ever since (more than three years) and fully accepted by the operations personnel. The project payout time was less than one year. The above technology helped the Beaumont O/A plant to achieve a NUMBER ONE RATING in North America in the Computer Control Index of the Solomon Associates Olefins Plant Rankings. The Beaumont O/A plant also ranked second in the world Computer Control Index.