Oxychem Pipeline of Pearland, Texas uses BJ Software's RealFlex host computer software to run their pipeline SCADA system. This 1,000 mile parallel pipeline transports ethylene and propylene from Corpus Christi, TX to Mt. Belview, TX and on to Lake Charles, LA at pressures up to 2,000 PSI.
Host Computer System Upgrade Justification
Costs associated with maintaining and implementing changes on the previous system easily justified the replacement/upgrade to a RealFlex SCADA system. The RealFlex system not only provides a user-friendly, menu-driven configuration format, but also offers a true real time interrupt driven operating system in addition to providing a multi-tasking and multi-user capability. This unique PC functionality is provided by the QNX operating system.
RealFlex System Description
The system architecture consists of a RealFlex system at the Pearland, TX and Markham, TX offices. This RealFlex software system monitors 2950 I/O points, has 80 screens and 10 reports. Either of these RealFlex host systems can monitor and control the pipeline offline. The Pearland host system is the primary scanner to the 51 RTUs, 12 PLCs, and 2 flow computers monitoring 1,000 miles of parallel pipeline. Algorithms were written in "C" and Control Sequence Language (CSL) to provide line pack (predictive loading) information via P, T, and Flow measurements.
Data Telecommunications System
RealFlex is running 5 different communications protocols simultaneously via 12 communications ports: Allen Bradley, Modicon MODBUS ASCII, Daniels DANSCAN, Valmet Tejas, and OXYSCAN (OXYSCAN is Modicon MODBUS with a check before operate feature). The data communication links are via a 14-channel 2-GHz analog microwave backbone with 900-MHz and spread spectrum radio communication to the pipeline RTUs. The communication system permits 20-second updates with a 10-second potential after completing scan optimization.
Future SCADA System Upgrade Plans
Oxychem plans to add hot back-up automatic fail-over at the primary host computer, upgrade the RealFlex system to the POSIX standard version in 1995, increase the number of RTUs on the pipeline and optimize RTU can rates. Following this, evaluation of leak detection software packages will occur for the planned addition of a transient model, leak detection system.
