Inferential control is the most profitable part of multivariable control (MPC). Inferentials can also be implemented without MPC, capturing the benefits of inferentials without the cost and difficulties of MPC.
Typical crude unit or fractionation section inferentials include distillation cutpoints of the naphtha, jet fuel, diesel, and gas oil products, plus related variables, such as RVP, flash, freeze and cloud point.
Benefits are often in the hundreds of thousands of dollars per year on larger crude units, based on improved production rates and quality.
Inferentials can be utilized in place of actual online analyzers, whether for operator information, cascaded to product flow controllers, or multivariable controlled variables (CVs).
Read "An Inferntials Update", by Allan Kern, P.E., an ISA InTech cover story and learn:
- how to achieve "high bar" inferential performance
- using an SQC spreadsheet to achieve lab load reduction
- using automated bias updates to improve performance and simplify operation
- using bias trends to reveal actual inferential performance
- how to easily perform a "sanity check" validation and audit inferential performance
