Online Two-Dimensional NMR Flowing Fluid measurements

Online nuclear magnetic resonance (NMR) is an efficient fluid detection method for fluid flow measurement. In our previous work [1] , the effect of velocity on the motion NMR measurement was studied and the velocity correction method was proposed. However, the effect of flow state on NMR measurement is more complicated than the effect of motion velocity. For the flowing fluid NMR measurements, the NMR response is influenced by both measurement velocity and the flow characteristic of the fluid sample.

The simulation result shows that the effects of plug flow and laminar flow [2] with the same velocity on T2 spectrum are almost the same, with similar migration from the static spectrum. Therefore, to analyze the effects of flow velocity on the measurement of NMR relaxation times, all of the flow modes can be considered as plug flow with the same average velocity, thus, velocity correction method is applied.
For the inhomogeneity of B0 and B1 fields, the apparent diffusion coefficient increases under flow state; the experimental results show that by using multi-magnetic and separate antenna structure, the rated flow velocity almost has no effect on the T1 measurement, and the effect on T2 measurement is reduced. By combining the DEFIR pulse sequence [3] , the measurement of T2, which is quite sensitive to molecular diffusion, is replaced by that of T1, which is insensitive to molecular diffusion. By adopting this pulse sequence on the multi-functional low-field and online NMR fluid analysis system can be used for online two-dimensional (2D) NMR flowing fluid measurement.