Chemical Processing - April 2008 - (Page 41)

MAKING IT WORK << Control performance supervision enhances revamp Upgraded ethylene cracker achieves targeted production rates in record time By Mikko Rönkä, Borealis Polymers Oy, and George Buckbee, ExperTune, Inc. Borealis operates a facility in porvoo, finland, that produces ethylene, propylene, butadiene, acetone, phenol and polyethylene. the complex, which employs almost 900 people, is integrated with a refinery upstream. in the spring of 2007, Borealis upgraded an ethylene cracker there. to get a solid return on the millions of euros invested in the project, it was essential to meet the target production rates each week once the ethylene unit came online. the company realized that improved control performance was crucial to achieving that goal. With almost 1,000 control loops in the ethylene cracker and only a few control engineers, Borealis needed to focus efforts on the most important areas. Project scope the revamp was designed to increase annual capacity from 330,000 tons to 380,000 tons. the project included equipment upgrades to a gas compressor, hydrogen purification unit and several distillation columns. regulatory and advanced process controls (apc) were updated to handle the modified process. for the advanced controls to deliver the best results, all regulatory controls must properly function. www.chemicalprocessing.com Without any dedicated tools or techniques for control loop monitoring, Borealis relied heavily on instrument maintenance and control engineers to detect problems. this reactive approach meant that only the most obvious and visible problems were addressed. equipment repairs were based on age of service rather than objective measures of condition. Without the tools for continuous monitoring, problems often progressed to the point of failure before being reported and corrected. to prepare the controls for successful startup, the company adopted three major strategies: 1. operator training with a simulator; 2. revision of APC; and 3. improvement of regulatory controls. Operator training — ethylene crackers average five years between turnarounds, so operators don’t develop much experience with startup and shutdown situations. to fill that experience gap, Borealis installed an operator training simulator. the simulator trains operators to handle: • startup; • shutdown; April 2008 • 41 http://www.chemicalprocessing.com

Table of Contents Feed for the Digital Edition of Chemical Processing - April 2008

Chemical Processing - April 2008 Contents From the Editor ChemicalProcessing.com Field Notes In Process Energy Saver Compliance Advisor Is It a Tragedy or Comedy for Engineers? Better Understanding Boosts Mixer Scale-up Don't Err With Air Compressors Control Performance Supervision Enhances Revamp Process Puzzler Plant InSites Equipment & Services Product Spotlight/Classifieds Ad Index End Point

Chemical Processing - April 2008

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