CORRECTION FOR K FACTOR OF GAS TURBINE FLOW METER |
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| Xue Chunling, Lv Deyue, Sun Yanzuo |
- Abstract:
- According to the International Standard ISO 9951 all gas turbine flow meters should have a maximum permissible relative error of ± 1% over the higher flow range (from 0.2 Qmax to Qmax), in the lower flow range (Qmin to 0.2 Qmin) the maximum permissible relative error is ± 2%. Usually the linearity of k factors, in percent, is used to express the basic relative error of a gas turbine meter. That means in the higher flow range the gas turbine meters shall have maximum permissible linearity of ± 1%, and in the lower flow range the gas turbine meters shall have maximum permissible linearity of ± 2%. The method commonly used to determine the mean k factor, K0, is: At first, the values of K< sub>max and K< sub>min are found out in the higher flow range, and then the mean K factor, K0, is calculated. Finally, the maximum deviation of K factors from K0 in the higher and lower flow ranges are evaluated to make an error judgment. In some cases this method might introduce a bias error into the K0, because the shapes of K factor signature curves ( the different modes of K factors distribution in different flow range) were not considered. Therefore, it is necessary to make different corrections for K0 in different cases. Our approaches are as follows: When K< sub>min appears in the lower flow range and the K< sub>max appears in the higher flow range, K0 = (A K< sub>max + K< sub>min) / 2, here A = 1.0099; When the K max appears in the lower flow range and the K< sub>min appears in the higher flow range, K0 = (B K< sub>max + K< sub>min) / 2, here B = 0.9902; When both the K< sub>max and the K< sub>min appear simultaneously in the same lower or higher flow range, K0 =(C K< sub>max + K< sub>min) / 2, here C = 1.0. During the individual calibration of each turbine meter this method has shown clear positive effects. While consideration was given to meter’s performance in the higher flow range, the performance of turbine meter in the lower flow range has been improved, therefore, more gas turbine meters are ensured to be up to standard. Based on the European Standard PrEN12261:1998 Turbine Gas Meter, the WME (Weighted Mean Errors) were calculated. The WME show that this is an easy method to obtain the proper value of mean K factor for gas turbine meter.
- Download:
- IMEKO-TC9-2003-041.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC9
- Event name:
- FLOMEKO 2003
- Title:
- 11th Conference on Flow Measurement
- Place:
- Groningen, NETHERLANDS
- Time:
- 12 May 2003 - 14 May 2003