Process Engineering Applications of Mobile Magnetic Resonance Measurements
- University of Western Australia, School of Mechanical and Chemical Engineering, Crawley, Australia
Hardware associated with benchtop NMR and MRI has dramatically improved over the past decade. This has enabled a range of potentially exciting applications to be explored across the chemical processing industries. However key to actual adoption is a distinct competitive advantage over alternative measurement options. Here we will detail three projects from our research laboratory with this broad requirement in mind. All employ relatively simple magnetic resonance measurement protocols, but are focussed on robust, repeatable and sufficiently quantitative measurements:
(1) NMR Multi-Phase Flow Measurements
We have previously reported on the use of Earth's field (EF) NMR detection to measure single phase flow using remote upstream polarisation [1]. We have recently extended this measurement platform to two-phase flow. The ability of the measurement to distinguish different flow regimes (stratified versus slugging) as required to subsequently model and hence measure liquid content and velocity will be discussed.
(2) NMR Measurements of Oil Contamination in Water Discharge
Parts per million (ppm) composition measurements are not a strength of NMR compared to alternative spectroscopies. Here, however, we will discuss the integration of a benchtop Magritek NMR device, featuring chemical shift resolution, into a Sold Phase Extraction (SPE) apparatus for concentration purposes, a process which we have fully automated. We now routinely measure oil contamination in water at ppm level precision and are able to distinguish between aromatic and aliphatic content. The device competes comfortably on price, accuracy and robustness with a commercial QCL IR equivalent.
(3) Early Detection of Fouling of Reverse Osmosis Membranes (ROM) Modules
We have previously reported on the use of signal moment analysis to provide an early detection of fouling of ROMs using EF NMR [2]. This method has however proved insufficiently robust for routine application. We have consequently developed a very simple NMR measurement of the amount of stagnant fluid in the ROM module and shown that it is equally able to provide the required early warning of fouling development [3].
References
[1] Fridjonsson, E.O, Stanwix, P.S. and Johns, M.L. (2014), Earth's Field NMR Flow Meter: Preliminary Quantitative Measurements, J. of Magn. Res., 245, 110-115.
[2] Fridjonsson, E.O., Creber, S.A., Vrouwenvelder, J.S. and Johns, M.L. (2015), Magnetic Resonance Signal Moment Determination using the Earth's Magnetic Field, Jnl Magn. Reson., 252, 145-150.
[3] Fridjonsson, E.O., Vogt, S.J., Vrouwenvelder, H.S. and Johns, M.L. (2015), Early Non-Destructive Biofouling Detection in Spiral Wound RO Membranes using a Mobile Earth's field NMR, J. Memb. Sci., 489, 227-236.