Nutzung moderner Technologien und Konzepte in der Grossgasmessung

摘要

At the present time in the field of the large gas measurements normally two meters are used,connected in series,which are based on different physical principles.These are the duty meter and the reference meter.Both meters should only have a low measurement uncertainty and should corre-spond to applicable legal regulations.This type of Installation makes it possible to use the advantages of redundancy and mutual monitoring.Usually before installation,the meters are checked and adjusted to a difference near"zero"on a high pressure calibration Station.In some cases immediately after installation in the plant unacceptable deviations between the meters can occur.This depends on the technological design of each Station.If the causes for this are not well-known or clearly identifiable,nowadays a renewed calibration of the meter usually has to be performed.This approach is very expensive and time-consuming.Also there is no guarantee for success,since the influences of the plant on the calibration Stands are lacking.Anotherpossibility exists in the use of an ad-ditional reference measurement,which cor-responds to the most current State of the art.These reference meters need to be high-pre-cisely examined,and if possible independent of external influences and stable over a long period of time.From VNG's point of view this article de-scribes the current State in the range of large gas measurement and the use of an 8-path ultrasonic meter in combination with a coriolismeter for investigating a custody transfer measurement.The two custody transfer meters had deviations of approxi-mately 0.8% in the process.The described approach is,according to the Station conditions,very economical since the meters do not have to be removed for error diagnostics and not taken out of opera-tion.Furthermore,we receive additional Information about the flow conditions of the Station.We have the possibility of determin-ing installation effects and other influences of the gas measurements.In addition to this,these results lead to the conclusion that in the future new possibili-ties concerning the calibration and the design of large gas measurements respectively become possible.