New Process NMR Analyser Revolutionises On-line Petroleum Analysis

Modcon Systems Ltd (Israel) has announced successful field installations of its new model MOD-8000 process NMR analysers. NMR is an electronic, non-optical method, which is based on assignment and quantification of hydrogen atoms according to molecular structures of substances. NMR analysers enable to accurately quantify physical properties in any process stream, transparent, dense and opaque alike. Its spectral response correlates linearly with the concentration of the components present in the process streams.

First NMR process analysers were launched in the late nineties of the last century. However, these were characterised by its high sensitivity towards temperature variations, which is the main drawback of these analysers. This deficient is very significant especially in those cases where process streams of different temperatures and viscosities must be measured. The overall new design of the third generation NMR process analysers comes to ensure successful application of this unique technology in refineries and chemical process industries.

To achieve maximised homogeneity and stability of the magnet, temperature fluctuations have to be insulated to prevent its influence on the magnet properties of the analyser. Therefore, the primary task was eliminating the high susceptibility toward any influence of temperature deviations between process streams. The new design included a total innovation in the concept of the entire hardware and software alike. The analyser contained a sample probe, surrounded by a 24 mm (previously 18 mm) bore sized magnet. The device also included power supplies for all the components, an NMR console to apply and detect RF signals of the RF coil in the sample line, within the magnet and of the RF coil on the reference probe, a shim system (for adjusting the static magnetic field to increase the homogeneity) with manually wrapped shim coils, and finally a heater controller which controls the magnet temperature. Initially, a total of seven electronic units were incorporated in the analyser (Shim controller, RF unit, PS unit, 19” rack PC, Heater controller, ADC and Timing board), but later their number was reduced to six.

The new model MOD-8000 process NMR analyser was successfully installed in two oil refineries, showing its high accuracy and reliability. In both applications this analyser was used to quantify physical properties of crude distillation unit streams including density, API, IBP, FBP, T10%, T90%, RVP, flash point, pour point, cloud point, freeze point, etc. When crude switching occurred, MOD-8000 minimised the impact on CDU operation by an immediate adjustment to shift the exact cut point, so that the maximum production capacity for each product towards the most valuable distillates was achieved.