(50g) Real-Time Optimization of Ethylene Furnaces Using Alternative Gas Chromatography and Mass Spectrometry

The paper presents the results of a magnetic sector mass spectrometer evaluation that was undertaken to determine the value, if any, of the fast analysis provided by this technology.  The methodology of the test was to characterize the comparative performance of alternative mass spectrometry (MS) and gas chromatograph (GC) technologies when used in conjunction with ethylene furnace advanced process control (APC) and a real-time optimization (RTO) control model. The site chosen was the Braskem olefins-1 unit located in Camaçari, Bahia, Brazil.

Whereas process mass spectrometers have been used as an alternative (lower cost) solution to multiple process gas chromatograph installations for many years, their use has been somewhat limited by their complexity - both real and perceived. The latest generation of process mass spectrometers has been designed to dramatically reduce the complexity by means of fault-tolerant design and automated setup but questions remain as to the value provided by the faster and more complete analysis that they provide. RTO models can operate effectively with relatively infrequent gas composition updates so multi-point gas chromatographs are often deployed. The evaluation was designed to answer the question “Does the fast analysis provided by the mass spectrometer result in significant benefits when the furnaces are operated using traditional RTO and advanced process control (APC)?”