Almost any cryogenic plant performance problem can be modeled and conclusively identified,since modern process simulators can accurately predict actual plant performance. This paper describesa systematic approach to plant troubleshooting based on process simulations. The proposedtroubleshooting logic should help operators and engineers minimize the time and expense necessary foridentifying cryogenic plant problems and deciding what to do about them.The recommended troubleshooting approach includes the following steps: (1) model theoriginal plant design; (2) simulate the expected plant performance for the current inlet conditions andpressure profile; (3) develop a model matching the actual field data; (4) analyze any process equipmentproblems; (5) simulate the target plant performance assuming no pressure profile problems; (6) analyzeany pressure profile problems; and (7) make changes in the plant to achieve acceptable plantperformance and verify the performance change with the models.A key feature of this approach is that process equipment problems are first distinguished frompressure profile problems and then either solved or accepted before analyzing any pressure profileproblems.When evaluating the economics of each potential modification, the plant models allow theengineer to quantify the corresponding incremental increase in product recovery. The goal of any planttroubleshooting effort is to achieve actual plant performance (product recovery) as close as possible tothe target plant performance, within the constraints of good economic sense. The techniques presentedhere should help in achieving this goal as quickly and inexpensively as possible.
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