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

A measuring device for measuring the level of a material contained within a container through a measurement opening in a wall thereof, comprising:

• a housing containing an electronics unit providing for the sending of microwave signals and for receiving characteristics of received microwave signals;
• a mounting flange attachable to the wall of the container surrounding the measurement opening, the mounting flange having an aperture therethrough which is aligned in registration with the measurement hole when the flange is attached to the container wall;
• a sending/receiving unit for sending and receiving microwave signals, the sending/receiving unit including a waveguide jacket, a waveguide filling media and taper element at least partially contained in the waveguide jacket, and a horn antenna attached at a throat end thereof to a lower face of the mounting flange in registration with the aperture in the mounting flange, the body of the horn antenna depending from the flange and projecting into the container through the measurement hole therein,
• the waveguide jacket having an internal bore opening therethrough along an axis thereof and having an external shape at one end thereof for axial insertion into the aperture of the mounting flange, the one end of the waveguide jacket and the one end of the horn antenna forming a pressure tight seal with the lower face of the mounting flange;
• the waveguide filling medium and taper element mounted in the internal bore opening of the waveguide jacket with a portion of the exterior walls of the waveguide filling medium being sealingly welded, soldered, or melted into the internal bore opening of the waveguide jacket thereby forming a pressure proof seal and for assuring that the container pressure impinges upon and is absorbed by the waveguide filling medium and the waveguide filling medium having the taper element depending therefrom and projecting below the mounting flange into throat of the horn antenna,
• an electrical transmission line connecting the electronics unit and the sending/receiving unit for communicating microwave signals between the electronics unit and the sending/receiving unit;
• and
• a spacer tube attached to the mounting flange;
• and
• a thermal barrier in the spacer tube, the thermal barrier including at least one low thermal conductivity wall that divides the spacer tube into consecutive sections.

A mounting assembly for a sending/receiving unit of a microwave instrument for the measurement of the level of a material in a substantially closed container having a measurement opening in a wall thereof, comprising

• a mounting flange attachable to the wall of the container surrounding the measurement opening, the mounting flange having an aperture therethrough which is aligned in registration with the measurement opening when the flange is attached to the container wall;
• a microwave horn attached at a throat end thereof to a lower face of the mounting flange in registration with the aperture in the mounting flange, the body of the horn depending from the flange and projecting into the container through the measurement opening therein;
• a waveguide jacket having an internal bore opening therethrough along an axis thereof, at least a portion of the internal bore opening having an insulating window inserted therein, the waveguide jacket having an external shape at one end thereof constructed and arranged for axial insertion into the aperture of the mounting flange, the one end of the waveguide jacket and the one end of the microwave horn forming a pressure tight seal with the lower face of the mounting flange;
• a taper element mounted in the internal bore opening of the waveguide jacket with a sealing ring circumferentially surrounding at least a portion of the body of the taper element for sealingly engaging the internal bore opening of the waveguide jacket;
• a spacer tube attached to an upper face of the mounting flange;
• and
• a thermal barrier in the spacer tube, the thermal barrier including at least one low thermal conductivity wall that divides the spacer tube into consecutive sections.

A measuring device for measuring the level of a material contained within a container through a measurement opening in a wall thereof, comprising:

• a housing including an electronics unit generating and receiving microwave signals and measuring characteristics of microwave signals;
• a sending/receiving unit sending and receiving microwave signals to and from the material, the sending/receiving unit including a waveguide, a waveguide filling media at least partially contained in the waveguide and an antenna, wherein the waveguide filling media forms a pressure proof seal with the waveguide to assure that container pressure impinges upon and is absorbed by the waveguide filling media;
• a mounting unit attachable to the wall of the container and supporting the sending/receiving unit in communication with the interior of the container for sending and receiving microwave signals through the measurement opening to and from the surface of the material;
• a spacer tube mounted between the housing and the mounting unit;
• a thermal barrier mounted in the spacer tube, the thermal barrier including at least one separation wall made from material of low thermal conductivity which divides the spacer tube into two consecutive sections between the electronics unit and the mounting unit for spatially and thermally isolating the electronics unit from the material;
• and
• a transmission line connecting the electronics unit and the sending/receiving unit for communicating microwave signals between the electronics unit and the sending/receiving unit, wherein the connection of the transmission line and the sending/receiving unit is located in the section communicating with the mounting unit.

A sending/receiving unit for sending and receiving a measurement signal into a pressurized container, comprising:

• a waveguide jacket having an aperture therethrough;
• a waveguide filling media at least partially contained in the aperture of the waveguide jacket, the waveguide filling media being adapted to connect to the waveguide jacket by at least one of soldering, welding, and melting so as to seal the aperture such that pressure from the container impinges on and is absorbed by the waveguide filling media;
• and
• an antenna connected to the waveguide jacket and adapted to direct microwave signals to and from a measurement hole in the container.

A sending/receiving unit for sending and receiving a measurement signal into a pressurized container, comprising:

• a waveguide jacket having an aperture therethrough;
• a waveguide filling media at least partially contained in the aperture of the waveguide jacket;
• means for sealing the aperture to assure that container pressure impinges upon end is absorbed by the waveguide filling media;
• and
• a microwave horn connected to the waveguide jacket and adapted to direct microwave signals to and from a measurement hole in the container.