Guided wave radar level gauge system with reduced end of probe reflection

Patent metadata

Field	Value
Publication number	US-9518858-B2
Application number	US-201414513538-A
Country	US
Kind code	B2
Filing date	Oct 14, 2014
Priority date	Oct 14, 2014
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

The present invention relates to a guided wave radar level gauge system comprising a transceiver for generating an electromagnetic transmit signal within a predetermined frequency range having a center frequency, a flexible single conductor probe having a first end connected to the transceiver and extending towards and into the product to a second end of the flexible single conductor probe; and a probe aligning member attached to the second end of the flexible single conductor probe for keeping the flexible single conductor probe substantially vertically extending from the first end to the second end. The probe aligning member exhibits a horizontal extension that increases with increasing distance from the first end of the flexible single conductor probe along a vertical distance greater than one half of a wavelength of the transmit signal at the center frequency. Hereby, determination of filling levels close to the bottom of the tank is improved.

First claim

What is claimed is:

1. A guided wave radar level gauge system, for determining a filling level of a product contained in a tank, said guided wave radar level gauge system comprising:
a transceiver for generating, transmitting and receiving electromagnetic signals within a predetermined frequency range having a center frequency;
a flexible single conductor probe having a first end connected to said transceiver and extending towards and into said product to a second end of the flexible single conductor probe for guiding an electromagnetic transmit signal from said transceiver through a tank atmosphere towards a surface of the product, and for returning an electromagnetic surface reflection signal resulting from reflection of said transmit signal at said surface back towards said transceiver;
a probe aligning member attached to said second end of the flexible single conductor probe for keeping the flexible single conductor probe substantially vertically extending from the first end to the second end,
said probe aligning member exhibiting a horizontal extension that increases with increasing distance from said first end of the flexible single conductor probe along a vertical distance greater than one half of a wavelength of said transmit signal at said center frequency; and
processing circuitry connected to said transceiver for determining said filling level based on said transmit signal and said surface reflection signal.

2. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member exhibits a horizontal extension that increases with increasing distance from said first end of the flexible single conductor probe along a vertical distance greater than 10 cm.

3. The guided wave radar level gauge system according to claim 1 , wherein said horizontal extension of the probe aligning member increases from a first horizontal extension substantially corresponding to a diameter of said flexible single conductor probe to a second horizontal extension being less than or equal to 5 cm to allow insertion of said probe aligning member through an opening at a top of the tank.

4. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member has a mass being greater than half a total mass of said flexible single conductor probe.

5. The guided wave radar level gauge system according to claim 1 , wherein said horizontal extension increases exponentially with increasing distance from said first end of the flexible single conductor probe.

6. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member comprises a substantially conical portion.

7. The guided wave radar level gauge system according to claim 6 , wherein said probe aligning member comprises a substantially cylindrical portion below said substantially conical portion.

8. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member comprises:
a first portion exhibiting said horizontal extension that increases with increasing distance from said first end of the flexible single conductor probe along a vertical distance greater than one half of a wavelength of said transmit signal at said center frequency; and
a second portion, further away from said first end of the flexible single conductor probe than said first portion, exhibiting a substantially constant horizontal extension.

9. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member comprises a vertically extending bore accommodating a portion of said flexible single conductor probe.

10. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member comprises a conductive structure with first and second longitudinally extending substantially planar portions forming an angle with respect to each other, and at least one fixing structure pressing said flexible single conductor probe against the probe conductive structure inside the angle.

11. The guided wave radar level gauge system according to claim 1 , wherein said probe aligning member comprises a plurality of flexible bars, each having a first bar end and a second bar end,
the first bar end of each of said flexible bars being connected to said flexible single conductor probe, and each of said bars, in an expanded state of said probe aligning member, extending from said first bar end in a direction deviating from the vertical direction to provide a tapered probe aligning member,
wherein at least one of said bars may be temporarily deflected to place said probe aligning member in a compressed state in which a maximum horizontal extension of said probe aligning member is reduced compared to said expanded state.

Assignees

• Rosemount Tank Radar Ab

Inventors

• Edvardsson Olov
• Larsson Michael

Classifications

• G01S7/02

  of systems according to group G01S13/00 · CPC title

• G01F23/284 Primary

  Electromagnetic waves · CPC title

• G01S13/88

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title