Browsing by Author "Swanepoel, Liam"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemDevelopment of a magnetoelastic resonance sensing system for water cut applications.(Stellenbosch : Stellenbosch University, 2018-12) Swanepoel, Liam; Müller, Cobus; Kosel, Jurgen; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: Precise measurement of the water fraction in oil (i.e. water cut) is of critical importance in numerous applications. In the oil and gas industry, for example, knowledge of the amount of water production and where it comes from is necessary before any remedial action can be taken. Currently, cost-effective, reliable and accurate measurement technologies capable of full range three phase measurements are not commercially available. The development of an ultra-low power, low-cost, wireless and non-corrosive resonance sensor is considered. The sensor is based on magnetoelastic technology that has been implemented by an amorphous ribbon and electromagnetic interrogation. The magnetoelastic ribbon’s resonant frequency is dependent on the vibrational damping effect of the surrounding medium, which in turn is determined by the dynamic viscosity of the medium. This enables distinguishing all three gas, water, and oil phases with measured sensor signal amplitude changes of 75% and 99% and resonant frequency shifts of 0.46% and 3.88% respectively, compared to the gas phase. The sensor shows sensitivity in the water-cut range from 10% - 90% WC and is characterised by a linear response from 10% - 80% WC. When immersed in water/oil emulsions the sensor power consumption ranges from 160 nW to 500 nW. A rapid decay of the magnetic properties has been observed in high salinity solutions due to corrosion of the sensor material, which represent typical environments in industrial applications. A solution for this has been found through coating the sensor ribbons with Teflon by dip coating, acting as an anti-corrosion layer that enables sensor deployment for extended periods of time in harsh environments. This study shows that a magnetoelastic resonance sensor possesses the required characteristics and sensitivity which make it suitable for use in water-cut applications. The possibility of inline WC measurement has been explored through the design of a modified sensor housing. The sensor incorporates a set of excitation and detection coils and allows the flow of liquid across the amorphous ribbon surface. Tests conducted in a flowrate controlled water flow loop show a shift of 150 Hz in resonant frequency from flowrates of 0.2 m/s – 0.63 m/s due to the increased surface drag on the sensor surface. However, this is considered insignificant as viscosity induced shifts are in the kHz range, therefore concluding that the sensor is insensitive to variations in flow rate. Furthermore, the sensor system design is expanded as a Portable Readout Device (PRD) capable of in-field measurements. The design consists of a battery powered microcontroller circuit that integrates with a smartphone via a mobile application. The peak frequency data sampled from the sensor is displayed on the smartphone. The PRD sampling algorithm has been tested with a 100% correlation in sampled data compared to a bench setup using Helmholtz coils and an oscilloscope. The PRD consumes 3.25 W of power during sampling and is capable of remote operation through the implementation of Bluetooth connectivity.