A method for radar-based gauging of the level of a substance in a tank (13) having at least one interfering structure (16 a-c), comprises the steps of: (i) transmitting a microwave signal in a plurality of radiation lobes (15 a-b; 15 a-d), each of which being individually directed towards the substance and at least one of which being directed towards the interfering structure; (ii) for each of the radiation lobes detecting temporally resolved the microwave signal as reflected against the substance, and for at least one of the lobes detecting the microwave signal as reflected against the interfering structure; (iii) based on signal strengths of the detected microwave signals, distinguishing the detected microwave signals, which have been reflected against the substance; and (iv) based on a propagation time of at least one of the microwave signals distinguished as those, which have been reflected against the substance, calculating the level of the substance.

Method and apparatus for radar-based level gauging

The invention concerns a microwave level measuring device for measuring of material levels in containers, suitable for operation at extreme container conditions, comprising high temperatures, high pressures, and/or chemically aggressive substances.

Fluid level measuring device measuring fluid level in a container at high temperatures and/or high pressures and/or in a chemically aggressive environment using microwaves

For measuring the level of a material in a container on the basis of the radar principle, microwaves are radiated downwards and reflected microwaves received by means of the antenna of a ranging device arranged above the highest level anticipated. In the normal measuring operation the received microwaves are evaluated in the distance range up to empty distance corresponding to the distance of the antenna from the bottom of the container for determining the echo waves reflected from the surface of the material, for measuring the transit time of the echo waves and for computing the distance of the material surface from the antenna of the ranging device from the measured transit time. In order to reliably detect the empty condition of a container having a curved bottom, despite the multiple reflections of the microwaves reflected from the container bottom, when no echo waves are detected in the distance range up to the empty distance, the evaluation is done in an enlarged distance range and any echo waves detected in the enlarged distance range beyond the empty distance are assigned to the empty distance.

Radar-based method of measuring the level of a material in a container

A radar level gauging system (1) for determining a filling level of a product (9) contained in a tank by transmitting and receiving microwave signals over at least two functionally independent channels Each channel has an electronics unit (3a, 3b) with transceiver circuitry (31, 32) arranged on a printed circuit board (34) and processing circuitry (33) connected to the transceiver circuitry (31, 32) for determining the filling level based on a relation between transmitted signals and received signals, and each electronics unit (3a) is electronically and galvanically separated from other electronics units (3b) The system further comprises a single antenna (4) for emitting microwave signals into the tank, and a hollow waveguide (5) for guiding microwave signals between each transceiver circuitry and the antenna Each electronics unit further comprises feeding circuitry arranged on the printed circuit board, the feeding circuitry comprising at least one feeding probe (36) protruding into the waveguide for feeding the microwave signals into the waveguide The present invention enables a very simple, cost-effective and reliable feeding for each channel

Multi-channel radar level gauge system

Contamination at the exciter of a parabolic antenna can lead to impaired signal quality, or even system downtime. According to a sample embodiment of the present invention a parabolic antenna is provided, which in addition to a parabolic reflector and an exciter has a rinsing device, which is configured so as to rinse and clean the exciter with rinsing agent or protect it from contaminants. Herein, the rinsing agent is injected, dropped, or else blown from a rinsing outlet in an outlet member at the parabolic reflector onto the exciter. Mounting the rinsing outlet directly to the parabolic reflector allows for the exciter to be cleaned from the parabolic reflector.

Parabolic antenna with rinsing connection

A device for gauging the level of a fluid in a container includes a floating roof, a transmitter for feeding a first microwave signal downwards in the direction of a fluid surface of the fluid, and a receiver for receiving a reflected microwave signal. The device includes a collector located above and in the vicinity of the floating roof, collecting the first microwave signal producing a collected microwave signal. The device also includes a vertical wave guide passing through the floating roof. The vertical wave guide guides the collected microwave signal to the fluid surface, and receives a reflected microwave signal reflected from the fluid surface. The vertical wave guide then guides the reflected microwave signal back to the collector and further to the receiver.

Kurt Olof Edvardsson

Papers

A method and apparatus for level gauging using radar in floating roof tanks