Noninvasive dielectric sensor and technique for measuring polymer properties
AssigneeE. I. Du Pont de Nemours and Company
InventorsMichael McBrearty, Stephen A. Perusich
Life of this patent
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Abstract
A sensor which allows dielectric measurements to be made on a high temperature product such as a molten plastic flowing in a conduit. It comprises a ceramic cylinder with an interdigitated electrode capacitor patterned into the inside wall. Uses of the sensor include continuous determination of copolymer composition and polymer viscosity (molecular weight) in a completely non-obstructive manner.
Claims25
A sensor for making complex permittivity measurements in-line in a fluid conduit without obstructing the flow of the process fluid, said sensor comprising a non-conductive shell having a bore therethrough, a pair of interdigitated fringing field electrodes on the inner surface of the shell, the electrodes being spaced from each other by 0.1 to 10 millimeters, an electrostatic shield on the outer surface, and means for conducting electrical current to one electrode and from the other electrode.
A process for continuously measuring properties of a fluid material flowing in a process stream
- a. contacting a sensor wherein said sensor has a non-conductive shell having a bore therethrough, a pair of interdigitated fringing field electrodes on the inner surface of the shell, the electrodes being spaced from each other by 0.1 to 10 millimeters, an electrostatic shield on the outer surface, and means for conducting electrical current to one electrode and from the other electrode, with the fluid material, the sensor being positioned completely non-obstructively in the process stream;
- b. generating an electrical voltage difference to be applied to the electrodes;
- c. measuring the electrical current through the sensor;
- d. calculating capacitance, dissipation and dissipation factor;
- and
- e. comparing the calculated values to predetermined reference values.
A sensor for making complex permittivity measurements in-line in a fluid conduit over a frequency range of about 0.5 to about 10,000 Hertz, said sensor comprising a non-conductive shell having a bore therethrough, a pair of interdigitated fringing field electrodes on the inner surface of the shell, an electrostatic shield on the outer surface, and means for conducting electrical current from one electrode and to the other electrode.
Dependencies are inferred from the claim text.