SwRI: Magnetic Resonance: Effective Process Monitoring Technology

Magnetic resonance (MR?also called Nuclear Magnetic Resonance or NMR) is a safe, nonradioactive, noncontacting, nondestructive, and selective measurement technique based on the interaction of matter with static and radio-frequency (RF) magnetic fields. The technique is performed by placing the material to be measured in a static magnetic field, applying a pulsed RF field, and analyzing RF signals from the material.

Use of Magnetic Resonance Measurements

Magnetic resonance methods are used to detect the amount of a selected element (e.g., hydrogen, fluorine, aluminum, phosphorus, sodium) present within the sensor?s sensitive volume. MR signals also contain information related to the viscosity of the material?s constituents and bonding of the selected nuclei to the lattice and other similar nuclei. Quantitative measurements can be made of:

Weight/Density	In uniform materials
Pressure	In gases
Flow	In simple and multiphase materials

The addition of the viscosity-related information in the signals enables determination of:

Composition	Solid/liquid/gas ratios, moisture content, oil and fat content, solids content
State	Freezing/melting points, liquid/gaseous phases, state of cure of thermoplastics and resins, polymer cross-linking, oxidation

Examples of industrial applications (on- and off-line) addressed by SwRI include:

Moisture Determination	Chemical products, food and agricultural products, wood and wood products, coal, soil, concrete, composites, slurries
Composition	Chemical products, fuels, composites, food and agricultural products, wood and wood products, mineral slurries, drilling muds
Energy Content	Fuels, natural gas, coal
Changes of State	Deterioration of lubricating oils, curing of resins, adhesives, polymers, aging of asphalt, food products
Detection	Contraband, explosives, contaminants

Advantages of MR Technique

Applicability	MR sensors are applicable to almost any area of industry
Configurations	Flowing product, sampled stream or one-sided access
Product Distribution	Measures properties throughout the bulk material
Volumetric Distribution	Ratio of the various components without weighing product or filled volume
Industrial Compatibility	Simple, rugged, reliable and nonhazardous
Noncontacting Sensors	No physical contact between the product and the sensor required
Product Quality	Quantitative information on the binding states

Industrial MR System Development

MR has been used successfully to monitor industrial processes on-line and at-line. Typically, it has been explored when other, more common off-the-shelf technologies failed to provide the required results. Some of the MR applications have demonstrated remarkable repeatability and stability. The instrumentation has proven to be rugged, dependable, accurate, and useable to control a process. Savings due to reductions in out-of-specification product, which is either recycled or disposed of, has justified the cost of the on-line instrumentation.

Southwest Research Institute (SwRI) has the facilities, staff, and expertise necessary to complete all aspects of the development of customized MR systems from the initial technical concept through the installation and servicing of instruments in limited quantities. SwRI has multiple specialized MR systems in its laboratories to perform measurements on samples over a wide range of temperatures, magnetic field strengths, RF frequencies, and other operating conditions. These initial measurements are made to determine the applicability of MR to solve a process monitoring problem. SwRI has had continuous activity in MR for industrial applications for almost 50 years and will continue to develop effective solutions for the food industry.

For more information about magnetic resonance and effective process monitoring technology capabilities at SwRI or how you can contract with SwRI, please contact Todd Goyen at tgoyen@swri.org or (210) 522-3528.