New Approach for Furnace Severity/Conversion and TMT Inferentials Using SPYRO, AspenPlus and Aspen Online

Borealis' cracker in Stenungsund, Sweden was a very early adopter of APC for olefin plants. Already 1982, then owned by Exxon they introduced severity control for the furnaces together with selector based furnace constraint control and other furnace controllers. All controllers ran in Honeywell's PMX process computer on top of a TDC2000 DCS.  While the constraint control was moved to DMC 1995 the severity control, with improved regressed models, kept on running in the old system.

When Honeywell announced 2001 that support for PMX would cease 2007 a project was started to migrate all process control applications to a new Experion PKS system.  It was decided that instead of a translation of the old applications they would be combined in a single DMC for each furnace with severity calculations done by an on-line SPYRO.  While on-line SPYRO was used in RTO since 1996 the then common implementation of SAPC – SPYRO for APC, would introduce additional software to learn and maintain. The solution was to use a copy of the existing RTO model, trimmed down to contain only furnaces and the feed headers and speed it up to execute with the DMC frequency.  While this sounds easy there were several challenges that will be described in the presentation.