BP’s objective was clear; improve the reliability of the gas compression trains, as they have a significant impact on the plant’s revenue stream.
The Hugoton Gas Field is the largest gas field in the continental United States. The field, extending from Kansas to the Texas Panhandle, was discovered in 1922, and reached commercial production in the 30s. Although production reached its peak in the early 1970’s, the Hugoton field is still a very large producer with over 8,000 wells of which 2,000 are owned by BP.
BP’s Jayhawk gas plant, near Ulysses Kansas, is the major gas processing plant serving the Hugoton tri-state area. Many gas producers besides BP depend on the plant for processing. The plant is fed by five separate pipelines with approximately 450 MMSCFD of gas being processed daily. The plant processes NGL and four other gas streams which are piped to other BP customers.
The gas is compressed via three motor driven geared compression trains. Each train drives tandem Cooper-Bessemer (Rolls-Royce) RCB multi-stage barrel type centrifugal compressors. Flow through the fixed speed compressor train is controlled by suction throttling. The control systems were En-Tronic® FT-50, as part of the original equipment supplied by the rotating division of Cameron, which is now Rolls-Royce Energy Systems. The dated controls had been causing spurious shutdowns that interrupted production.
United Controls Group was awarded the project to replace the En-Tronic® FT-50 system. The work included a new Rittal TS panel with the same footprint as the existing panel. The Class 1 Division II area classification was addressed by utilizing a Pepperl + Fuchs purge / pressurization system. The FT-50 system was replaced with a state of the art Allen-Bradley ControlLogix PAC and A-B’s Flex I/O modules. The original FT-50 vibration monitoring was replaced with a Bentley Nevada 3500 system. The FT-50 surge control was migrated into the ControlLogix PAC. Start, stop, sequencing, load and capacity control as well as safety monitoring are all integrated into the PAC using RSLogix5000 programming software.
Local operation is achieved by the addition of a 15” color PanelView touch-screen HMI. This enabled the operator staff access to real-time data without having to communicate via radio to the main control room. Yard and recycle valve operation was also programmed into the HMI, allowing complete local control. The Unit Control Panel to DCS communication was accomplished using a Prosoft communications module, allowing communications via Modbus Plus, a Master/Slave Fieldbus based on RS-485 transmission technology, already widely utilized at the plant. UCG equipped the Control Room with an HMI running Wonderware which communicated to each UCP via a fiber optic Hiper-Ring network.
Prior to shipment, the Jayhawk control systems were connected to hardwired, point-to-point simulation equipment for internal verification, simulation, and customer witness tests. This thorough approach to testing insures that each system is validated and ready for installation in the field. The Jayhawk project was an overwhelming success with all the compressor trains being commissioned within 5 days after completion of loop checks.