Steam Cracker Optimisation through On-Line TOPNIR™ Analysis and Rigorous Kinetic Models

Near-infrared spectroscopy is now a well established technology for the indirect measurement of hydrocarbon streams composition and properties. From the earlier works and patents in late 80's, several industrial applications have been derived and implemented, mostly in the refining area but also in steam cracking plants. Here, it allowed implementing a full feed forward and predictive control of the furnaces using real time NIR analysers for the liquid feeds, whilst GC analysers didn't provide such accurate and fast response time analysis. Recently, new published works showed the growing interest of this technology applied to olefins plants.

At Lavera, the steam cracker of naphtachimie (a 50/50 subsidiary of INEOS Olefins and Total Petrochemicals) is the first one over the world equipped with an on-line TOPNIR™ analysis of naphtha feedstock. The 26 furnaces of the plant produce more than 740,000 tpa of ethylene. The naphtha represents between 70 and 95% of the whole feedstock of the plant. Between 1991 and 2003, these furnaces were controlled by an in-house on-line process control model which was using 13 naphtha properties provided from TOPNIR™ on-line analyser to adjust in real time the furnaces operating conditions.

Thanks to the high level of accuracy of TOPNIR™ analysis linked to SPYRO® performances, the optimisation of steam cracker operations allows a substantial induced benefit in the range of 1-2 M$/year.