Geothermal Steam Measurement with Orifice Plates: Cerro Prieto Update

Abstract

Last year CFE analyzed the problems related flow measurement. To certify the steam flow rates in the delivery points in the Cerro Prieto Geothermal field, where this steam is received by the operation team and used in for electricity generation. In 2005 one of these points was inspected and the possible problems evaluated in order to meet the ISO 5167 standard requirements and obtain a possible certification. At this time, the code was studied and the pressure taps and the internal roughness of the pipe were the most significant problems to be solved as well as the circularity of the pipe, because the code ask for a tolerance +/- 3% and ASME accepts +/- 5%. With this experience, CFE decided to sign a contract with the Centro Nacional de Metrología (CENAM) the official institution responsible to deliver a certificate and verify a 36 inch pipe transporting steam for Cerro Prieto IV. The physical measurements and the results of this experience are presented.