FCC CO Boiler Reconditioning, Saves Client $150,000,000

NEC Past Project
Project FCC CO Boiler Reconditioning
Location US Gulf Coast
Scope Of Work Consultation on FCCU Emissions Control Project, CO Boiler Mechanical Evaluation, CO Boiler Performance Evaluation & Field Testing, Mechanical Component Design, Turnaround Planning, Field Supervision
Project Summary A large refinery was developing a Fluid Catalytic Cracker (FCC) emissions control project with a major multi-national engineering company. The engineering company recommended installing a new 1,500klb/hr, 600 psig CO Boiler and ancillary equipment designed to withstand 3-5 psig flue gas back pressure. The installed cost of the new CO Boiler was estimated to be in excess of $150,000,000 representing over 60% of the total project cost. The client wanted another opinion and contacted Norton Engineering. After evaluating the existing CO Boilers (built in 1969), and the emissions control options recommended by the client’s engineering company, Norton Engineering identified several low cost upgrades to increase the flue gas side design pressure of the existing CO boilers and further recommended a change in scrubber technology to reduce the boiler back pressure resulting from the installation of downstream pollution control equipment. The changes to the project scope (different scrubbing equipment) and the boiler upgrade / reconditioning work, which cost less than $5,000,000, were successfully implemented in 2008/2009 saving the client over $150,000,000 in capital expenditures.

Project Detail

FCC CO Boiler Reconditioning, Saves Client $150,000,000

A large refinery client on the Gulf Coast was installing a new Flue Gas Scrubbing system to remove particulates and SOx from their FCC Flue Gas.  This new pollution control equipment would increase the back pressure on the existing CO Boilers, and an initial evaluation by a large engineering/construction contractor recommended a full replacement of the CO Boilers, at a estimated capital cost of over $150 Million.  The refinery contacted Norton Engineering to review the recommendation, and our boiler and combustion experts felt that the boilers could be upgraded with fairly minor structural improvements and operate safely and reliably at the higher operating pressure.  Norton Engineering was hired to evaluate the boilers and provide detailed guidance on required mechanical changes to operate at the higher pressure.

Project Details

Chief tasks in execution of this project included:

  1. 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.
  2. Development of mechanical designs for increasing the stiffness of buck-stays, roof and floor supports and the strength of corner brackets.
  3. 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.
  4. 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.
  5. Development of detailed execution plans for field work to be accomplished during an FCC turnaround.
  6. Evaluation of boiler CO gas control and bypass systems including redesign of automatic atmospheric vent system and components.
  7. Redesign of CO boiler expansion joints to allow minimum effort, minimum cost, and quick replacement.
  8. 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.
  9. 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 with higher flue gas back pressure resulting from the installation of emissions control equipment on the boiler exhaust.  Estimated savings in capital investment by upgrading instead of replacing is over $150 million.

The client subsequently contracted Norton Engineering to support a second stage of emissions control for the FCC which further increased the back pressure on the existing CO boilers. Norton Engineering evaluated the CO Boiler mechanical components for the higher operating pressure, as well as evaluated different operating modes to ensure safe and reliable operation with the additional pollution control equipment. Norton Engineering also reviewed the next phases of the project which were completed by the same large multi-national engineering company that did the planning and detailed engineering for the first project phase.

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