Retrofitting: How to have successful revamps in stead of failed projects
By Andrew W Sloley
Contents
Retrofitting: how well will it work in your plant?
Starting a successful revamp
Moving from the plant test to conceptual design
Conclusions
References
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Retrofitting: how well will it work in your plant?(Return to Contents)
Retrofitting a plant is often seen as an attractive investment option compared to a new plant. Implementing new technology ‘creeps' the plant capabilities at minimum cost. Plant debottlenecking for incremental capacity or product quality changes costs less than a new plant. While generally true, care must be taken. Some plants are all neck and no bottle. Which is your plant?
Historically, most project and design techniques have focused on new plants. Even with new construction, performance has been poor. Surveys have shown [1] that new construction meets success criteria in less than 20 percent of capital projects. Experience with retrofits shows an even lower success rate. Lack of success on previous retrofits is often a major reason operating plants are reluctant to proceed with changes. Unforeseen consequences of projects can eliminate years of profits. How can a plant assure a successful revamp instead of a failed project?
Starting a successful revamp(Return to Contents)
Successful revamps require many different elements [2]. Nevertheless, starting on the right path at the beginning tremendously improves success rates. The two starting elements are (1) building the right revamp team and (2) understanding current operation.
First, a brief review of team importance: "In the final analysis, people, not procedures, make a project successful." [3] Never forget this point, and do anything it takes to get the right people for your job: especially in a revamp. Procedures only account for standard situations. By definition, revamps are not standard situations. Limits and capabilities of the existing plant must be recognized and used. Every plant is different. None fits a standard mold. Depending on people, supported by sound engineering principles, not on mindless application of procedures, is the basis for success in a fast-track retrofit.
Second, the current operation of the plant needs understanding. Every plant is different. Every facility has different limitations and spare capabilities. These can vary greatly from the calculated values of how the plant is supposed to run based on paper documentation. Plant testing defines the current plant performance. Analysis of plant performance identifies real limits and potential in the unit.
Insist on a plant test. Plant testing is vital to a successful revamp. Examining performance of the real process and equipment surpasses the usefulness of any modeling or engineering calculations. The basic techniques for successful revamps all hinge on plant test results [4].
Good test run data identifies areas of concern for the retrofit team as well as potential areas to avoid investment and modifications. To assure that an effective revamp, the owner must realize (1) necessity of the plant test and be prepared to pay for it in money, personnel commitment, and time and (2) insist that all organizations involved take it seriously.
Moving from the plant test to conceptual design(Return to Contents)
Plant test analysis allows for meeting objectives with minimum modifications. Minimum modifications reduce investment and cost. Every item that does not have to be changed is one less thing to pay for or to have to execute during a turnaround. How do you minimize the amount of work required in the plant while making sure that you modify everything that must be done? The answer is simple, have a very good defined plant test of the existing operation and test operations on all the major equipment items.
Plant tests identify required changes early in the revamp work. From the test run data, the first step should be a prompt evaluation of major equipment items and utility systems. By major equipment items and utilities we include:
Detailed engineering is not required at this point. What the revamp team requires for this step are experienced engineering generalists. The evaluating engineer must understand operations, equipment design, and procurement to an extent to make an informed and prudent engineering judgment with limited information. Equipment specialists should become involved as needed. When pushing the limits of equipment, problems encountered only rarely in normal types of operations may occur. The main questions to answer are "What is the limit of the existing shell, casing, fire box, or other major constraint?" and "What is the ultimate limit of that size item in this service?" Answers to these questions define the major modifications required.
As an alternative to straight replacement of major equipment items, modifications to the process flow scheme should be evaluated at this stage. Process flow scheme modifications can often selectively unload flows from one equipment item to another.
Integrating process scheme changes and equipment modifications and service changes generates the conceptual process to meet the revamp objectives. The plant test analysis and data again play a pivotal role. Knowing what true capabilities are available, the benefit of modifying process changes can be accurately determined. Without plant test results, changing the process becomes a hit-or-miss affair with high risk. Plant test results minimize technical risk and assure the most effective revamp process scheme.
Conclusions(Return to Contents)
Revamps can be attractive for plant operators and owners to improve overall plant performance. The most important things to remember during the start of the revamp effort are (1) people, not systems, are the keys to a successful revamp and (2) true current plant performance must be understood.
References(Return to Contents)
[1] Merrow, E.; Yarossi, M. E. Managing capital projects: where have we been- where are we going? Chem Eng October 1994:108-111.
[2] Sloley, A.W. Fast-track revamp projects (working title). To be published in Chem Eng.
[3] Horwitz, B. A. Keep Attila the Hun off your project. Chem Eng Prog April 1995 (91) 4:37-41.
[4] Sloley, A. W. Reducing the danger of maintenance exposure. Petroleum Technology Quarterly Spring 1998: 59-65.
About the Author(Return to Contents)
Andrew Sloley is a consultant in distillation and troubleshooting. He worked as a troubleshooter and consultant for Glitsch, Inc. from 1990 to 1995 and for an engineering company between 1995 and 1999. Previously, he worked as a process engineer in technology development and application for Exxon Chemicals. His experience covers a wide range of petroleum refining and petrochemical areas. He has authored or co-authored over 90 publications and conference papers. Papers have appeared in Oil and Gas Journal, Hydrocarbon Processing, Petroleum Technology Quarterly, Chemical Engineering Progress, Hydrocarbon Technology International, National Engineer, and others. Conference papers have included presentations at the National Petrochemical & Refiners Association, American Institute of Chemical Engineers, American Society of Mechanical Engineers, Japan Society of Mechanical Engineers, Chemical Engineers Australia, and others. He currently acts as a consultant to a variety of companies in the area of troubleshooting and distillation. Other current work includes both engineer and operator training for distillation operations, design, and troubleshooting. Sloley has a bachelor's degree in chemical engineering from the University of Tulsa, and is a registered professional engineer in the State of Texas. He resides in College Station, TX, and can be reached at asloley@distillationgroup.com or tel: 979-764-3975 (www.distillationgroup.com).