Phillips 66 converts aging DCS to Honeywell Experion PKS
Along the Gulf Coast, about 70 miles southwest of Houston, Phillip 66’s Sweeny, Texas, refinery has undergone a change. Over the past two years, the cogeneration facility at the highly integrated refinery has operated under the weight of an aging DCS system in need of a facelift.
“The DCS was installed in 2014, and we faced a lot of challenges with out-of-service components,” said Carlos Sepulveda, automation projects coordinator, Phillips 66 Sweeny Refinery, during a presentation at HUG 2025, this year’s gathering of the Honeywell Users Group in San Antonio, Texas.
He explained the process that the refinery, which boasts a workforce of some 1,500 employees and contractors, took to replace the old cogeneration unit DCS with a Honeywell Experion Process Knowledge System (PKS) designed to minimize risk, shorten project schedules, and avoid project overruns by employing next-generation project execution principles. He added the project was further necessitated by segregation from the refinery’s process control network, lack of alarm management and cybersecurity concerns and difficulties.
“Often, we had to make operating systems and cybersecurity updates using a third-party,” Sepulveda continued.
Field execution for the project began in October 2022 and followed an ambitious timeline of migrations. The last phase took place in 2024.
System configuration
The focus of the project was the refinery’s independent cogeneration unit where two new controllers were needed for all essential turbine control functions. The newly installed Experion C300-based control system features a redundant pair of controllers, a speed protection module (SPM), dedicated I/O modules, and servo valve positioner modules for turbine I/O.
Sepulveda said, with the new system, the SPM facilitates direct measurement of speed from the turbine’s active speed probes and manages high-speed trip I/O, while the dedicated I/O modules connect to standard field instrumentation. The servo modules ensure precise control of five servo-driven fuel gas control valves present in each unit. Honeywell supplied C300 controllers, firewalls, I/O modules, and fiber-optic connections in dedicated new Experion system cabinets.
Fuel control logic was vital to the project. “This is the heart of all of the control that we are doing,” Sepulveda said. The fuel gas control valves regulate each turbine.
In the new system, each pilot, as well as each A- and B-stage control valve demand parameters are determined by valve output trimmed by the actual flow. The calculated control valve determines the required control valve position. The actual calculated control valve is determined by the metered flow rate through the control valve.
Sepulveda explained that the pilot and the A-stage control valves open to their designated ignition demand position when the turbine starts up. After flame detection, the fuel gas control valves switch over to closed-loop operation. A dedicated sequence control module in the logic governs ramping the turbine from cold start to synchronization in several steps.
He added that each fuel gas control valve has a high flow monitor comparing the demanded signal and the actual control valve position feedback. A deviation outside of prescribed limits will trip the unit after a short-time delay.
Project execution
Sepulveda said the process migrating to the new Experion system wasn’t much different than other projects he’s worked on. However, there were some challenges to overcome.
He pointed out the creation of a new database as the top among them. “We had to spend a lot more engineering time for that particular part of the project,” he said. The primary reason was a lack of documentation associated with the old system. The refinery had several different owners over its lifetime before Phillips 66 took over. “We lost a lot of diagrams over the years,” Sepulveda said.
Other steps in the process included commissioning and unit startup, including programming and testing the human-machine interface (HMI) and logic conversion. Field construction included another challenging area, cabinet replacement.
“The process of ripping the old cabinets and installing the new Honeywell cabinets was a bit tricky,” Sepulveda said.
In addition, they had to account for onsite operator training, familiarization with the new HMI and troubleshooting.
Lessons learned
Sepulveda said if they did it again, they’d use the “keep it simple” method. He advised analyzing the process first, then building out the DCS logic. “Our objective was to fully migrate the DCS logic into the Honeywell Experion C300-based control system,” he said, “but the outcome featured numerous additional and unnecessary function blocks.”
The exercise could have been streamlined by employing standard Honeywell function blocks and configuration templates. “We could have focused on analyzing the control modules and modifying execution periods as necessary for improved processing speed and fewer overruns,” he said.
Sepulveda also learned that involving operations from the beginning is key. He advised involving the appropriate people in the factory acceptance test (FAT). “We engaged a skilled and committed operator who paid close attention to the details,” he said.
In the end, Sepulveda and the refinery team were quite pleased with the outcome. “I think it was a very successful project,” he said.
