In-situ calibration of permanent magnet flow meters in PFBR using noise analysis technique

• Published in: Flow measurement and instrumentation Vol. 34; pp. 76 - 82
• Main Authors: Ramakrishna, Ranga, Anup Kumar, P., Thirumalai, M., Vijayakumar, G., Suresh kumar, V.A., Suresh Kumar, K.V., Prakash, V., Rajan, K.K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2013
• Subjects: Cross-correlation technique; In-situ calibration; Permanent magnet flow meters; Permanent magnet flow meters; Cross-correlation technique; In-situ calibration
• ISSN: 0955-5986; 1873-6998
• DOI: 10.1016/j.flowmeasinst.2013.08.004

In Fast Breeder Reactor sodium circuits, permanent magnet flow meters (PMFM) are extensively used to measure the liquid sodium flow rate. The performance of PMFM can degrade with respect to time due to various reasons. This degradation results in reduction in output voltage and affects flow meter stability. The distortion of the magnetic field in the large diameter flow meters makes its characteristics nonlinear. Further, the performance of the flow meter is also affected by vibrations, shocks, temperature and change of reluctance within the magnetic circuit. Hence, it is desirable to calibrate the PMFM at periodic time intervals for ensuring accuracy and stability. However, it is very difficult and almost impossible to calibrate large size flow meters once installed in the system under actual flow conditions in a sodium test loop. Therefore, it is necessary to calibrate the flow meter in-situ without disturbing its normal operating conditions.
Experiments were carried out in different sodium loops in Fast Reactor Technology Group (FRTG) and Fast Breeder Test Reactor (FBTR) with permanent magnet flow meters of different sizes to develop an in-situ calibration procedure. Cross-correlation technique is studied and the flow rate is estimated from the transit time with a deviation of ±5.5%, which is comparable with that of calibration of the flow meter in actual sodium test loop. In this paper, in-situ calibration of PMFM is discussed with experimental details, data acquisition, cross-correlation technique and the results obtained.
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•Experiments were carried out with 40, 100 and 200 ND flow meters in sodium loops.•Measurements are also carried out with electrode distances of 15, 30, 36 and 72mm.•Cross-correlation technique is developed and the flow rate is estimated using it.•The deviation of the flow rate estimated is found to be within ±5.5%.•This technique can be used for in-situ calibration of PMFMs in FBR.