APC Background

The on-line multivariable predictive controller MVAC is using dynamic models and the stored past of the MVs, to predict the future evolution of the CVs; then it calculates the MV moves necessary to get
All the CVs inside their limits
The MVs as near as possible to their targets : e.g. feed maximization
These calculations are performed on a process control computer, which reads the data from the process, and writes back the modified setpoint to DCS controller.

Benefits

The quantifiable profits generated by Axens APC are mainly due to the respect of the specifications and the production increase (1.5 to 5 %). They generate benefits which typically vary between 0.5 and 2 M€ per year, or even more depending on the units (type, size...).

Axens' APC provides solutions to:

Maintain constant product quality (neither over- nor under-quality)
Stabilize the process
Minimize product variability
Minimize process disturbances
Anticipate and react to feedstock changes
Monitor catalyst deactivation
Increase catalyst run lengths
Optimize economics
Reduce CO2 emissions

Axens' APC key features

Each process is examined from the perspective of Axens' feedback and operational know-how
Proprietary inferential modelling technology
Proprietary multivariable model-based controller named MVAC capable of managing wide range of functions

Axens as a single source supplier

Axens offers the complete line of APC services following a rigorous step by step procedure including:
1. Site survey and Pre-Tests
2. Functional design
3. Inferential customization
4. Automated Step testing and dynamic modelling
5. Controller tuning
6. Off-line tests with dynamic simulator
7. Operator instructor training
8. Commissioning
9. Post audit
10. Remote monitoring
11. Maintenance

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