Client Goal

• Eliminate Production Environment out-of-tolerance conditions for Dew Point and MUA control.
• Produce solid software architecture for repeatable, scaleable results
• Increase Energy Efficiency
• Reduce Valve and Instrumentation wear  

Project Overview

Tegron provided consulting engineering services to eliminate Production environmental conditions benchmark variances for dewpoint control. Variances occured during changes in ambient temperature and operating conditions during equipment start and weather changes.

Scope of Supply

• Process Consulting
• Design
• Software Development
• Client Operator and Engineer Training
• Startup and Commissioning

The Outcome

• Provides a needed artificial load for the glycol if started prematurely without affecting fab dewpoint.
• Provides backup means to control dewpoint during a weather front if the operators do not start glycol in a timely fashion.
• Provides bumpless transfer to/from chilled water control from/to glycol control.
• Uses one PID to control 4 valves with wildly varying gains. It automatically adjusts for the different valve gains to provide linear control across the entire PID’s range regardless of the change in control element (valve) characteristics. This a resulted in dramatically less valve travel thus increasing valve life and reducing compressed air usage and improves process variable control
• Each valves’ high and low clamp can be changed independently. The code recalculates the PID output in 1 scan to ensure the valve does not make a dramatic move if these clamps are changed while the valve is controlling dewpoint.
• Humidification and dehumidification are precluded from running simultaneously.
• Large energy savings over the course of a years especially in spring and fall when weather patterns change frequently.
• Heating / cooling coils are preemptively “primed” for use prior to their being needed providing for a bumpless transition when moving through the PID’s range and thus differing control elements (valves).
  Filters out process noise before the PID reducing valve travel. This combined with the fact that the PID executes at a periodicity as dicated by the process and not each PLC scan cycle allowed for large derivative values to be used in the PID thus minimizing the effects of stiction and hysteresis.
• Reduces load on the PLC.