Maximizing Compressor Performance

Abstract Maximizing Compressor Performance Process engineering services monitoring compressor performance is vital to successful maintenance of plant efficiency and energy use.  Process gas compression equipment is key in moving process fluids through chemical equipment as well as providing the necessary pressure to promote chemical reactions.  An Ammonia plant Process Air compressor was upgraded with high efficiency impellers, diffusers and improved seal technology with resultant performance improvement monitored for three years.  The compressor originally was designed employing 1970's technology, and the upgrade improved capacity about 15%, while improving stage efficiencies by about 6% Polytropic efficiency gain.  The article highlights the benefits of monitoring, improving and preserving compressor efficiency.
		Process gas compression equipment is essentially the "Heart" of plants, moving process fluids through chemical equipment as well as providing the necessary pressure to promote chemical reactions.  This article highlights maintaining and improving the performance of centrifugal compressors.  Centrifugal compressors by their design have inherent aerodynamic and thermodynamic performance and efficiency characteristics, dependent on size, shape and the number of impellers as well as the condition of shaft and inter-stage seals. Recent improvements over the past 10-15 years include new impeller shapes incorporating complex 3-D enhanced curve shapes for blading and the use of new materials and designs for shaft end and inter-stage seals.  These vendor improvements have boosted compressor efficiencies by 5-7 percentage points, reducing energy consumption while improving compressor capacity. An Ammonia plant Process Air compressor was upgraded with high efficiency impellers, diffusers and improved seal technology with resultant performance improvement monitored for three years.  The compressor originally was designed employing 1970's technology, and the upgrade improved capacity about 15%, while improving stage efficiencies by about 6% Polytropic efficiency gain.  The design basis and actual performance data is illustrated as Table 1, Process Air Compressor Data, with graphical representation of efficiencies shown in Figure 1.  The compressor equipment arrangement is illustrated in Figure 2, Compressor Flow Diagram.  The prior performance before retrofit is not shown, however, the compressor did achieve the capacity and efficiency improvements previously noted.