For its new 1,4-butanediol (BDO) plant in Lima, Ohio, BP Chemicals has used Emerson Process Management’s PlantWeb field-based automation architecture with Foundation fieldbus. In the development of the system, BP distributed most process-control logic to field devices rather than centralising control in traditional computer control systems.
The BP Chemicals project is believed to present the most extensive use of ‘truly distributed’ control using FOUNDATION fieldbus, with control algorithms running in 83 of the architecture’s 85 Fisher Fieldview digital valve controllers. In addition, all dual-element transmitters rely on on-board signal-select blocks. Seventy-one fieldbus segments serve 350 Rosemount, Rosemount Analytical, Micro Motion, and Fisher Controls fieldbus instruments and valves handling 130 feedback loops.
Each of the process’s 400 discrete devices is hardwired to DeltaV automation system process controllers. Therefore, the entire system, with the exception of an emergency shutdown function, is covered by a single operating platform. The automation was configured graphically by simple drag-and-drop methods. Pre-engineered function blocks included almost all logic; seldom was there need to write code. All valves were calibrated in place and all instruments relied on the manufacturers’ certified calibrations – eliminating need for a costly calibration trailer during construction.
Operators can see valve movements on their displays, which is very helpful when balancing flows or determining if a valve is poorly tuned or sluggish.