Case Studies > ProcessLogix, Another Industry First for ITS Provides DupontSA With Fibre for Growth

ProcessLogix, Another Industry First for ITS Provides DupontSA With Fibre for Growth

Industrial Technology Systems (ITS) has integrated another industry first for one of its ‘Blue Chip’ clients. The DupontSA T7 plant in Teesside UK produces Terephthalic Acid for the production of fibre, film and resin polyester.  When its management checked for Millennium compliance and capability for expansion, they realised that the existing PDP Auditor system used for controlling the Oxidation and Purification plants needed replacing. 

ITS, the local Rockwell Solution Provider (Process), who managed the project believed that the new Allen-Bradley ProcessLogix solution would be perfect for the application.  DupontSA engineers also felt that the system was more flexible than the alternative PLC and SCADA solution.

As ITS’ project engineer explained, “ProcessLogix is user friendly because it is Windows driven and represents graphically what could previously only be seen numerically.  This means that operators require less training and information is readily available from the screen.  Basic PID control and loop tune facilities are easier as they are faceplate driven for plant optimisation.”

The system collects data from approximately 150 plant inputs.  It scales and spans the values to engineering units and passes them by a modbus comms link to the production area Management Information System - the SuperCoAuditor (SCA) system.  It needs to do this at least every thirty seconds but can do it every four, if required.

It performs five separate supervisory, complex, closed-loop schemes in automatic mode.  Seven analogue output signals are sent from these loops as remote setpoints to single loop, panel-mounted controllers. The ProcessLogix system screen displays provide the operator interface for these loops to switch between local and computer mode, change setpoints and tune parameters.  The system is able to display live and historical trends of any of the values in its real time database.

The system is also used to raise alarms for alerting operators to events on the plant.  Some are raised by a digital output from the ProcessLogix system, which is connected to the conventional panel-mounted alarm annunciator system in the control room. The rest are raised on the ProcessLogix Alarm screen.

ProcessLogix is a completely new control and automation architecture. It takes the strengths of both PLC-based systems and DCS-based systems and combines them into a single integrated solution. At the same time it gives users like DupontSA a common platform to use across both its discrete and process applications.

ITS replaced the PDP11 computer in the oxidation control room with ProcessLogix and replaced the system I/O in both control rooms.  Its main function is to monitor the critical parameters used to calculate set points on the seven control loops.  These are critical to the quality and performance of the polyester plant. It also communicates critical and other plant parameters or data to the DupontSA supervisory system.

The ProcessLogix server and workstations run on a standard PC with the Allen-Bradley ProcessLogix package running a Windows NT 4.0 platform.  The controller and I/O equipment are part of the package that consists of four 10-slot racks.  The oxidation control room houses three of the racks and the fourth is in the purification control room.  Connections between the I/O racks are made via a ControlNet network, using an optical fibre link.

ProcessLogix controls a sample switching system for a pair of on-line analysers that can be switched between three different samples.  It controls the digital outputs to three solenoid valves and performs the required "sample and hold" to provide measurement of two composition measures for all samples.

“The drag and drop editor reduces the design time needed for the control functions,” added ITS’ project engineer, “while the system architecture of ProcessLogix and the method of assigning standard faceplates significantly reduces HMI configuration time.”

Philip Hastings, lead engineer at DupontSA feels that “the system provides an excellent platform for enhancing the process control of the plant.  It has a comprehensive trending facility and is much more operator friendly.” 

Clearly ProcessLogix has had a positive impact at DupontSA, and the system is likely to find a home in other parts of this DupontSA plant and beyond.


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