Z-Way™ (Fuzzy Logic)

Z-Way™: An easy to use Multivariable Controller allowing operator experience and chemical engineering principles to be easily converted into membership functions for online fuzzy control:

• Controller Configuration based on Fill-in-the-Blanks and Click/Select Type options
• Avoid Costly and Difficult Plant Tests
• Reduce Application Implementation Time
• Field Proven and in-use on Commercial Distillation (Azeotropic) Towers

Technology: A four step approach to map input data nonlinearly into outputs:

• Fuzzifier - Models the behavior as a matter of degree, rather than in precise discrete categories
• Rules - Based on simple operating heuristics and engineering principles (e.g. If Tray is Cold Then Decrease Reflux by a Small Amount)
• Inference Engine - Based on the values of the inputs (e.g. multiple tray temperatures), the Z-Way controller checks all the rules and activates the sub-conditions to be made in the outputs (e.g. reflux flow, reboiler steam flow)
• Defuzzifier - Similar, but, opposite of Fuzzification, the output membership function is converted into a practical number which can be implemented by a PID controller

Other features:

• Time Based Hold on Output Option-Useful for Slow Processes
• Multivariable - 6 Inputs X 2 Outputs
• Script (VBA) add-on to allow nonlinear and ad hoc customization
• Embedded OPC Client for easy interface with DCS systems

Typical Z-Way (Fuzzy Logic Controller) Usage:

• Temperature Control - Dynamic Adaptation of PID constants (warm-up phase, steady-state, cool-down)
• Processes too complex for PID schemes and too costly to implement MVPC technology - Binary Distillation towers (Demethanizer, Propylene, etc., columns)
• Batch reactors
• Polymerization reactors