Pipeline Stage Design For Increased Operating Range.

Abstract

With the continuing increase in energy demand, pipeline compressors are being challenged to cope with both large flow rates and broad operating range flexibility, driven by the local seasonal markets. Overall, high efficiency still needs to be maintained, as compressor efficiency will significantly impact on gas transportation cost. Those joint requirements call for significant improvements in pipeline compressor stage design. This intends to highlight the experience gained in the development of these challenging stages in a unique effort combining experimental and computational fluid dynamics (CFD) studies. In particular, the study started with the detailed testing of a conventionally designed stage. Careful comparison of CFD versus test results was followed by intensive activity coordinating between CFD and testing. The intent of those simulations was to identify the limits of this initial design and to indicate the guidelines for improvement. The massive use of state-of-the-art CFD allowed investigation on a large number of impeller configurations. Analysis of the numerical results suggested the possibility of significant operating range improvement with minimal penalty on efficiency and choke limit. An intensive experimental test campaign confirmed the validity of the new impeller design for improved operating range improvement but also highlighted the balance between efficiency and operating range requirements. A final optimization on a statoric component is then performed to get back to original efficiency while retaining increased operating range.