Lubricant processing has traditionally accounted for a relatively small percentage of a refinery's production volume. However, com-pared to fuels processing, the lubricants products command high values. This has led to an increasing emphasis on optimum lubricants production. Successful revamp projects must take into account all parts of the lubricants manufacturing plant. The operation of the initial unit in the lubricant plant, the vacuum lubricant column, will have a large effect on the downstream units and the total lubricant plant economics.
Correct project definition and economic analysis for lubricant vacuum column revamps requires a detailed knowledge of the feed composition, the downstream processing, and the production objectives. Definition of the feed composition to the lubricants column is most successfully obtained by a full analysis of the existing products and back-blending to synthesize a unit feed stream. This feed charac-terization must cover all of the expected feed compositions or blends to allow for proper unit design.
With accurate data, design of a revamped lubricant vacuum column can proceed. At this stage, detailed heat and material balances must be examined. Areas to cover include the effect of different feed slates and compositions, product slates, and operating rates. The heat and material balances for each expected operation need to be examined to provide a realistic design range and flexibility requirement for the equipment design. With the correct basis for equipment design, mechanical considerations can be examined with confidence. Major mechanical considerations include operability, run-length assurance, installation practicality, and materials selection.
The case study included covers in detail a revamped vacuum lubricant tower. The selected case makes specific points to illustrate the subjects covered. This case study demonstrates that, while complex, revamping a lubricant vacuum tower can be successfully accomplished if sufficient attention is paid to detail in all phases of the project execution.
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