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FCC DeButanizer Revamp for Flexibility and Additional Capacity
Daryl W. Hanson
CITGO Petroleum Corporation
Lake Charles, Louisiana
Mike R. Resetarits
In the past few years, the refining and chemical industry (referred to as operators throughout the paper) have placed an emphasis on maximizing the value creation of each individual unit in the plant. This goal of maximum value creation has placed importance on the operators to maximize capacity of each unit to the major equipment bottleneck. The competitive marketplace has dictated that while operating at maximum capacities for the major equipment, the operators find ways to operate reliably for a four to six year run length or more.
The two goals of maximum capacity and reliability have placed economic emphasis on the revamps that occur during the unit shut-downs. Operating companies that select to revamp units are placing more responsibility and pressure on the equipment vendor to insure that the goals of the revamp are secured during post-revamp operation. Many times, the goals for distillation units include:
- Pressure Drop.
Since many of the goals above are intertwined, it is important that the operator realize the importance of the vendors experience when involved in the retrofit design.
Operators have determined that it is more economically feasible to fix a problem with a solution that is 100% correct, than to start-up and have a failure with a solution that is only 50% correct. Operators are finding that it is getting increasingly important to revamp towers with the least risky option. This is especially true for the "fixed equipment" in an operating facility. By fixed equipment, the authors are referring to equipment that can not be revamped or replaced on-line. The fixed equipment commonly causes the rest of the operating facility or other supporting units to be shutdown before a revamp can be initiated. Causing an operating facility or supporting unit shut-down is a large economic impact that all plants should avoid to be competitive.
The authors wish to share a complete case study of a recent FCC Debutanizer revamp. We say complete because the original revamp of the distillation column was undertaken in 1995. In 1995, the tower was revamped from conventional trays to a "High Capacity" mini-valve tray. After not meeting the capacity goals that the operator had intended, the tower had to be revamped asecond time in early 1999 to achieve the original goals for the revamp. We will describe the complete troubleshooting exercise, provide operating data & scans for the revamps, and provide the economics that were realized.
Link to Paper