5-1 Introduction

The virtual plant is a relatively new concept that is easily confused with existing simulation methods for process design, configuration checkout, and operating training systems. Users may not realize that most of the existing batch process simulations are off line and noninteractive and that most of the real-time dynamic process simulations were originally designed for continuous processes. These real-time process simulations can develop severe numerical errors or even fail under the extreme conditions of batch operations and require interfaces for communicating I/O, controlling inventory, and coordinating with the control system in speeding up, slowing down, pausing, or resuming. The control system engineer is probably most familiar with tieback simulations since these have been predominantly used for configuration checkout and operating training systems. The process response in these tiebacks is mimicked by the trial-and-error adjustment of ramp rates. Ramps are triggered by the manual inclusion of flow path logic to include the opening and closing of valves or the turning on or off of pumps.

Section 5-2 of this chapter discusses the key features that distinguish a virtual plant from existing simulation systems and itemizes the important advantages of the virtual plant approach. Section 5-3 provides a spectrum of uses for virtual plants. Section 5-4 concludes with the basic requirements for and issues concerning implementing a virtual plant. These last two sections note the role of a bench-top system with an industrial control system in getting the most out of a virtual plant. This chapter shows how a virtual...