(194d) Guidelines for Specifying and Evaluating New and Rerated Multistage Centrifugal Compressors

Refineries, petrochemical companies, and gas processors are continually trying to increase plant production while budgets are getting tighter. Rerating process centrifugal compressors has become an ever-increasing trend as a solution to this problem. Existing hardware, however has it's limitations. The limiting factors can be different for different applications of the same equipment When rerating existing compressors cannot adequately meet increased compression production demands , new equipment must be added to the existing plant or a new plant must be built. Both of these scenarios require the purchase of new compressors. Realizing that eventually a new plant may expand of increase production to respond to increased demand, and that the differential cost for a new compressor is high, it makes since to consider the future uprateability of new compressors when they are initially purchased and built. Discussions in this paper will give those involved with rotating equipment guidance when evaluating the design of a centrifugal compressor-either new or rerated, including a list of items that should be reviewed: and guidelines that should be followed. A case study and examples will be used to emphasize and help explain the various limiting factors for both new and rerated multistage centrifugal compressors. Cost implications and tradeoffs along with the impact on reliability will also be analyzed. With this information those involved with rotating equipment will be able to work to effectively optimize compressor hardware selections for the required process duty.