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Implementing a Fluid Catalytic Cracking Unit (FCCU) Control and Safety System Upgrade

Keeping You On-Line. Moving You Ahead: Our Solution-Savvy Approach

Addressing Technical Obsolescence and the Vulnerability of Systems

A long-standing refinery client approached M S Benbow (MSB) to engineer a solution to
upgrade their problematic FCCU Control and Safety System. The heart of the FCCU system was a Power Recovery Train (PRT) that consisted of a steam turbine, an axial compressor, and an electric motor that was used to aid in startup; the electric motor then would switch to generator mode once the PRT was on-line, driven by the connected steam turbine, thereby producing power for the refinery. The existing Fault Tolerant control systems for this complex application consisted of a Safety Shutdown System, as well as a Surge Control System for the axial compressor. Several issues led to the decision to upgrade the existing systems; among them were the increasing difficulty in securing spare parts and software support, as the systems faced obsolescence. In many instances, refinery personnel had to resort to internet auction sites to find spare parts, then send them to a third-party certifying company for inspection and refurbishment.

At the request of the client, MSB’s first tasks were to conduct Front End Engineering Design (FEED) to investigate potential deal breakers, and to develop a Total Installed Cost for the entire project, within 10%, which was a prerequisite for management approval. Once FEED and the cost estimate were completed, MSB received management approval and quickly moved onto the Detailed Design phase of the engineering project.

As soon as the Detailed Design phase began, three major tasks were identified as critical path: the in-depth field investigation to determine the condition of the existing wiring and terminations; creating the required drawings and delivering to the turnaround planning team in time to meet an extremely aggressive schedule; and lastly, the reverse engineering of the existing control systems, as documentation was poor to non-existent.

Field Investigations – Managing the Unexpected

The Field Investigation Phase. Among the most critical issues during this phase were the conditions of the existing marshalling panel and wiring terminations. MSB was challenged with replacing a control panel that had been exposed to a corrosive environment for many years. As a result, all field wiring terminations had deteriorated to the point that the system experienced spurious trips when the control panel door was opened. To address this issue, MSB developed a plan to disconnect all field wiring, replace all the terminals, redress all the existing wiring from all the field devices, and re-terminate and torque all connections.

Meeting Project Deadlines – A Dual Approach

MSB was awarded the project one and a half years before the scheduled turnaround, which provided only six months to perform all the field related engineering and design, since the field portion of the design packages were required one year before the turnaround for planning purposes. Even with a planned outage at a refinery, there are high-stakes involved. Turnarounds can face unexpected problems. The team at MSB had earned the trust of facility leaders and operational managers by delivering on-time due to its disciplined approach to system upgrades and implementations. After conducting exhaustive field investigations, MSB identified all the field work that could be done pre-turnaround and the field work that could only be done during the turnaround; and provided design packages for each. By identifying all work that could be done pre-turnaround, MSB helped the client mitigate the risk of the turnaround overrunning the aggressive schedule.

Design and Reverse Engineering – Reconstructing and Improving the System

The client’s existing system had minimal documentation. As a result, outside of a limited number of personnel at the refinery, there was no one else who had a solid understanding of the control systems’ operation; and worse yet, fewer who could make modifications or troubleshoot problems. MSB started with an in-depth review of the existing control software and reversed engineered the functionality to develop a full set of documentation which explained, in detail, the operational characteristics of the system. MSB then conducted a step-by-step review with the client to evaluate the functionality, correcting latent issues and making enhancements to assure a smooth migration to the new control system. This fully vetted description of the functional operation then became the basis for the design of the new control system, providing enhanced control and eliminating legacy issues experienced with the older control system.

From Design to Implementation to Commissioning – Testing is Critical to Success

Once the design was complete, MSB developed procedures for both the Factory Acceptance Test (FAT) and Site Acceptance Test (SAT). These procedures detailed all testing necessary to assure a safe, reliable, and functional system before leaving the manufacturing facility, and also after field installation. The FAT was coordinated by MSB, and involved simulation of system operation and all alarm/shutdown scenarios. All wiring and IO points were also fully tested prior to shipment to the field. The SAT, conducted on-site after installation, was also coordinated by MSB engineers. Testing involved wiring and loop checks to verify the quality of the field installation process. Throughout the field installation and test phase, MSB engineers were on-site 24 hours a day to provide technical direction and supervision. After the extensive test process was complete, startup and commissioning the new systems went smoothly and quickly, and the FCCU was back online well in advance of the turnaround deadline.

The MSB Solution: Getting you on-line on time.

With a proven design procedure and extensive experience, M S Benbow delivered the two control systems for the client’s FCCU within the turnaround schedule’s constraints, while allowing the client to operate its systems more reliably and safely. MSB team members acted as an extension of the client – as true partners – to move from conception, to design, to installation, testing, and implementation.

Services Provided

  • Constructability Review
  • Construction Support
  • Cost Estimate Development
  • Existing Control System Field Verifications
  • Factory Acceptance Test Execution
  • Factory Acceptance Test Procedure Development
  • Front End Engineering Design
  • HAZOP Review Participation
  • Instrumentation & Controls
  • P&ID Assessment and Revisions
  • PLC Cause & Effect Development
  • PLC Functional Description Development
  • PLC Specification and Design
  • Pre-Turnaround Construction Package Engineering & Design
  • Record Drawing Development
  • Site Acceptance Test Execution
  • Site Acceptance Test Procedure Development
  • Startup and Commissioning Support
  • Turnaround Construction Package Engineering and Design


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