No matter how sophisticated, a process control system will at some point require operator intervention to function properly. Start-up and shut-down operations in particular tend to involve manual procedures that the control system can not handle alone.

Unfortunately, I find the very operations that require operator intervention the most are also the most infrequent. Training operators to handle these nonroutine situations can be difficult if the only classroom available is the control center itself. Shutting down a working process just to demonstrate how it is done can be extremely unprofitable, to say the least.

That's where ProTRAX from the TRansient and Analysis eXperts at the TRAX Corp. (Forest, Va.) comes in. With the software, users can create simulated plants where operators may train without jeopardizing the real process.

A ProTRAX simulation is comprised of graphical objects selected by the user to represent the individual components of the plant and its control system. By placing these objects on a blank screen and connecting them as they are connected in the plant, users can construct a complete simulation without writing a single line of computer code. The simulated functions of each object have been pre-coded to act just like the real thing.

Well, almost. Each object comes equipped with various parameters that users must define to customize the generic object to a particular application. ProTRAX asks the user for the object's physical data and operating point data (such as valve sizes and tank capacities) as those objects are placed on the screen.

ProTRAX takes it from there and automatically creates a Fortran program to run the simulation. As the simulation progresses, each object is subjected to mathematical inputs from other connected blocks. These quantities represent the outputs that the connected blocks would in turn generate from their own inputs. The input-output relationships for each object are based on the first principle mass and energy relations that apply to that particular object.

Ultimately, all of the inputs in this input-output-input chain start with the operators. They have operator consoles that allow them to open simulated valves, ignite simulated furnaces, start simulated fans, etc. These inputs then determine how the rest of the simulation behaves. By observing the simulated plant's reactions to a certain choice of inputs, the operators learn how to run the real plant most efficiently.

Engineers too, can benefit from a ProTRAX simulation. They can observe how the plant would behave if a control system were modified or if a piece of equipment were to fail—all without disturbing the real plant.

There is one caveat to all this. Objects in the ProTRAX library are designed specifically for simulating fossil-fuel power plants equipped with boilers, turbines, heat exchangers, and the like. It is certainly applicable to related facilities like paper mills and wastewater treatment plants, but I wouldn't want to try simulating a biological or economic process with ProTRAX. That's not what it's for.

A complete ProTRAX system comes with all software required to perform fossil plant simulations, except for the Microsoft Windows NT operating system. The package even includes a Fortran compiler. ProTRAX may be configured to operate on multiple PCs and/or workstations, allowing parallel processing of plant simulation. Minimum requirements for a single PC installation are a Pentium PC, at least 32 Mbytes of RAM, and 120 Mbytes of hard disk space. Prices also vary. The price for a complete ProTRAX package in the U.S. is $30,000. Individual software modules are available a la carte.

For more information on ProTRAX, visit www.controleng.com/info.