Improving Orifice Meter Performance: A Case-Study of Orifice Metering Accuracy from Various Field Stations

摘要

New metering technologies offer many advantages over the traditional orifice flow meter. Despite the advantages, gas companies must consider the cost of upgrading an existing meter station before installing a new flow meter technology. Often times, the cost associated with an orifice meter replacement involves the cost of the new flow meter, as well as the associated cost of fabricating new meter runs, calibrating the meter and installing the meter and related instrumentation. Because these costs may not be justifiable at all meter stations, U.S. gas companies still rely on orifice flow meter measurement throughout the majority of their pipeline systems. Panhandle Energy estimates that orifice meters make up approximately 80-90% of the meters in the company’s pipeline network. Due to the need to account for gas more accurately and reliably, Panhandle Energy conducted a series of tests aimed at studying the performance of orifice meters under various operating conditions. Orifice meter runs from various Panhandle Energy meter stations were tested at the Southwest Research Institute Metering Research Facility (MRF). The orifice meter accuracy (and possible bias) was determined using a reference standard provided by the MRF High Pressure Loop critical flow Venturi nozzles. The results of the study provided guidelines that can be used to justify the option of replacing an orifice meter with a new flow meter. When an upgrade to a new flow meter technology is not justified, the study found that the accuracy of orifice meters could be improved significantly by honing the meter tube to reduce the pipe wall roughness and/or replacing the 19-tube bundle with a plate-type flow conditioner.