FCC CO Boiler Reconditioning, Saves Client $150,000,000
Chief tasks in execution of this project included:
- A detailed mechanical evaluation of the original Combustion Engineering boiler design to determine the flue gas side pressure capability of all envelope components including: water walls, buck-stays, roof supports, floor supports, flue gas ducting, CO gas ducting, wind boxes, FD fans, etc.
- Development of mechanical designs for increasing the stiffness of buck-stays, roof and floor supports and the strength of corner brackets.
- Assessment of boiler performance including field testing to determine operating limits for maximum steam production and idling one boiler while the FCC continued to operate.
- Development of detailed boiler performance model, allowing evaluation of off-design operating conditions to support refinery turnaround planning, steam system optimization and allow evaluation of future FCC operating scenarios.
- Development of detailed execution plans for field work to be accomplished during an FCC turnaround.
- Evaluation of boiler CO gas control and bypass systems including redesign of automatic atmospheric vent system and components.
- Redesign of CO boiler expansion joints to allow minimum effort, minimum cost, and quick replacement.
- Technical support / supervision of turnaround field labor for initial inspections, determining the scope of work necessary for reconditioning items found during initial discovery inspections, designing and supervising fabrication of replacement parts as needed, inspecting and approving field work.
- Review of the project scope as proposed by client’s engineering contractor which resulted in changes in scrubber type, location, revised flue gas ducting design and, revised planning basis for future NOx control.
Both CO boilers were successfully reconditioned/upgraded during two separate 12 day turnarounds. The client had to delay the FCC turnaround due to equipment delivery problems and wanted to take one boiler offline to complete its reconditioning/upgrading. This schedule change necessitated operation of the FCC with one of two boilers on line, the first time that the refinery had run the FCC without both boilers on-line. Norton Engineering’s combustion specialists and mechanical engineers worked with operations to define FCC operating constraints during single boiler operation and provided technical support during transition and initial operating periods. Aside from allowing the work on one boiler to proceed outside the turnaround, saving significant costs, the refinery has demonstrated and gained experience with a single boiler operation so the in the future, CO boiler problems will not automatically trigger an FCC shutdown and the attendant loss of revenue.
Both boilers were brought back to original design capacity after the reconditioning work and have been operating for two years with higher flue gas back pressure resulting from the installation of emissions control equipment on the boiler exhaust.
The client has contracted Norton Engineering to support a second stage of emissions control for the FCC which will further increase the back pressure on the existing CO boilers. Norton Engineering’s efforts in the next phase of the project will be to complete work on boiler pressure part designs and supervise small additional boiler upgrades needed for the higher back pressure expected in the next project phase.
Norton Engineering has also been requested to review the next phases of the project, being completed by the same large multi-national engineering company which did the planning and detailed engineering for the first project phase.
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