Measurements of End Cap Temperatures in a Multistage Barrel-Style Centrifugal Compressor

Gas compressor customers desire to operate gas compressors at higher discharge temperatures. In barrel-style centrifugal compressors, dry gas seals are used to limit the leakage along the shaft from the process fluid to atmosphere. The temperature limit of dynamic O-ring seals in the dry gas seal cartridge is one of the primary limiters to operating gas compressors at higher discharge temperatures. While the present discharge temperature limit is conservative compared to the seal limits, without a detailed understanding of the thermal distribution around the discharge-side end cap, operation at compressor discharge temperatures that exceed seal limits has too much risk. Thus, this paper describes the approach taken to characterize the temperatures around the discharge end dry gas seal of a commercial C335EL centrifugal compressor. A phased test matrix with increasing discharge temperatures was conducted so that the temperature distribution throughout the end cap could be assessed. The full-scale, highly-instrumented compressor was operated at discharge pressures and temperatures ranging from 4.7 to 9.4 MPa (680 to 1370 psi) and 113 to 218 degree Celsius (235 to 425 degrees Fahrenheit), respectively. The experimental test set-up and results are presented herein. Results include demonstration of successful compressor operation at discharge temperatures greater than seal limits as well as the end cap temperature sensitivity to lube oil supply and dry gas supply temperatures.