Wet Gas Compression technology for centrifugal compressors is without doubts one of the topics that have enjoyed a most rapidly growing interest in recent years [1]. This is certainly due to the new opportunities for exploiting aging gas fields, which are rendered possible by this technology. However, despite the numerous recent works on this topic, the fundamental understanding of wet gas compression processes remains challenging in the sense that no unified standards for testing and performance exist, and that the understanding of the basic physical phenomena is not fully complete. The present work is concerned with such issues and contributes experimental results and performance analysis for a low pressure-ratio centrifugal compressor stage in heavily wet gas streams. An open loop test rig was built for a single scale model centrifugal compressor to be run at typical design operating range. The impeller was a standard impeller with no design adjustments for wet streams. The performance was assessed at liquid mass fractions (LMF) ranging between 0% and 50% and at average droplet diameters between 50 μm and 75 μm, as well as non-atomized liquid streams. The results clearly demonstrate that wet gas strongly influences compressor performance, considering adsorbed power, efficiency and compressor characteristics. The results also show that, although the impeller design did not account for heavily wet streams, the overall compression characteristics remain good and the machine was able to process the two-phase mixture without failures, in some cases with improved pumping. The compressor exit temperatures of the gas phase in heavily wet conditions are key to assessing machine performance, in particular efficiency, for wet gas compression. Although an accurate technology approach for measuring such temperatures has not yet been developed, in the present work a droplet model is proposed. This model is then calibrated with experimental data in order to develop a methodology providing reliable efficiency values.

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