Unstable Reading of Accelerometers in Cryogenic Service

Case Study− RasGas operates over 100 pieces of cryogenic submersible equipment. Approximately 80 % are on pumping service and the rest on expansion service. − These units use two vibration transducers to provide protection and diagnostic capability. The signal from the accelerometer is conveyed to the external signal conditioner (inside field junction box) them to a monitoring system − Since commissioning vibration signals tend to be spiky (that is, random in nature) they may OEM recommended alert limits. This may mask potential real problems to the machine

Unstable Reading of Accelerometers in Cryogenic Service

Case Study− RasGas operates over 100 pieces of cryogenic submersible equipment. Approximately 80 % are on pumping service and the rest on expansion service. − These units use two vibration transducers to provide protection and diagnostic capability. The signal from the accelerometer is conveyed to the external signal conditioner (inside field junction box) them to a monitoring system − Since commissioning vibration signals tend to be spiky (that is, random in nature) they may OEM recommended alert limits. This may mask potential real problems to the machine

Cavitation Performance Improvement of an Industrial Cryogenic Centrifugal Pump by Implementing Variable Pitch Inducer

LectureCavitation performance improvement of an industrial cryogenic pump is studied in this paper. A variable pitch helical inducer is designed and implemented to the existing pump assembly to enhance the cavitation performance in terms of Net Suction Positive Head (NPSH). Initially, Computational Fluid Dynamics (CFD) simulations of the pump assembly are conducted for the original configuration and the pump with new proposed inducer to determine the cavitating (two-phase) and non-cavitating (single-phase) performance. The Rayleigh-Plesset cavitation along with homogeneous fluid model is used to study the bubble dynamics under the assumptions of single fluid undergoing no thermal energy transfer between each phase. Experimental tests are conducted on the existing configuration of the pump and also with the new variable pitch inducer to determine the true performance in cavitating and non-cavitating operating conditions. Experimental results are compared to the simulations to validate the accuracy of the proposed numerical modelling and assumptions. NPSH with 3% (NPSH3) differential head drop is employed as a criterion to identify the true cavitation performance of each inducer configuration. It is found that, NPSH3 performance can be improved by 25% by replacing the existing inducers with the proposed new variable pitch inducer. In addition, with the new inducer there is minimal impact to the existing single-phase pump performance