Showing posts with label Guided Wave Radar. Show all posts
Showing posts with label Guided Wave Radar. Show all posts

Liquid Interface Level Measurement Using Guided Wave Radar, Magnetic Level Gauges, Float & Displacer, Thermal Dispersion, and RF Capacitance

Liquid Interface Level Measurement

The need for interface measurement arises whenever immiscible liquids - those incapable of mixing - reside within the same vessel. The lighter material rises to the top and the heavier material settles at the bottom. In oil production, for example, water or steam is used to extract oil from a well. Well fluids then route to production separators where they settle into their primary constituent parts as a water-hydrocarbon interface. Water may also be used as a transport medium or a cleaning agent and forms an interface with an allied material which is later extracted.

Knowing the position of a process interface is necessary for maintaining product quality and operations efficiency. The interface is measured and controlled by precision level switches and transmitters. Though at least 20 different types of liquid level measurement devices are in service today, only a very few are suitable for accurate and reliable interface measurement. Grouped by their operating technologies, these include Buoyancy (Floats and Displacers), RF Capacitance, Thermal Dispersion, Radar, and Redundant Technologies (those combining two measurement technologies in one instrument).

Interface Level Measurement
The five leading interface measurement technologies in use today are Guided Wave Radar, Magnetic Level Gauges, Float & Displacer, Thermal Dispersion, and RF Capacitance. These five leading interface measurement technologies in use today are discussed in the technical bulletin titled "Liquid Interface Level Measurement" and produced by Magnetrol International.


For more information on any industrial level control application, contact Miller Energy. Call them at 800-631-5454 or visit their website at https://millerenergy.com.

Guided Wave Radar - An Option for Level Measurement in Hygienic Applications

GUIDED WAVE RADAR LEVEL TRANSMITTER FOR HYGIENIC APPLICATIONS
A special version of the Magnetrol Eclipse 705
is configured for hygienic applications.
Image courtesy Magnetrol
Measurements of a variety of process conditions are utilized to monitor and control operations and output. One general goal of measurement, other than answering the question "how much", is to avoid or minimize any interference with the process itself. A second goal is to not be fooled by the process into returning a false measurement result.

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel from the emitting antenna via a fixed waveguide or probe immersed in the target medium. When it contacts the media surface, the pulse energy is reflected back along the probe to a receiving antenna. The instrument actually measures the time elapsed between the pulse transmission and the detection of the reflected return. The time measurement is used to calculate the distance from the antenna to the media surface. The distance calculation, with knowledge of the vessel, can be converted into a value indicating media level or volume. Of course, this is a simplified account of the operating principal.

Guided wave radar (GWR), as opposed to an open style radar level measurement method, uses a probe immersed in the process media to guide high-frequency electromagnetic waves into the media being measured. While it does involve contact by the sensing instrument with the media, GWR eliminates interference from fixtures or structures that may exist within the tank or vessel. The immersion probe waveguide also attenuates the impact of media turbulence and other potential disturbances. The waveguide reduces the potential impact of elements that may adversely impact the measurement accuracy, resulting in greater accuracy and reliability of the measurements.

For hygienic applications, the transmitters are available with 304 stainless steel housings designed specifically for use in facilities with the special requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries. In addition to high accuracy, the GWR instrument output is not impacted by media buildup on the sensing probe.

Share your level measurement challenges with process instrumentation specialists. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.


Top End Guided Wave Radar Level Transmitter

guided wave radar level transmitter
Magnetrol's model 706 embodies the best of guided
wave radar level measurement.
Image courtesy of Magnetrol
The Eclipse Model 706 is Magnetrol's loop powered high performance guided wave radar level transmitter. It incorporates many of the company's latest innovations into a single instrument capable of meeting the demanding requirements of an array of industrial applications.

Product improvements include increased signal to noise ratio, suitability for use with low dielectric media, and the ability to deliver accurate indication under foaming, flashing, or other challenging conditions. An extended probe offering enables use in measuring interface, liquified gas, even bulk solids.

The instrument is suitable for overfill applications, and does not use algorithms to infer measurements in a dead zone that may occur near the top of the probe in some other designs. The Eclipse 706 delivers true measurement right up to the process flange. Upgraded electronics allow the unit to be pre-configured prior to shipment, if requested. Additionally, the widest range of communications options is available.

For more information, share your level measurement challenges with a process measurement specialist. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.


Summary of Technologies Used For Continuous Liquid Level Measurement in Industrial Process Control

non-contact radar liquid level transmitter
Non-contact radar liquid level transmitter
Courtesy Magnetrol
Automated liquid processing operations in many fields have requirements for accurate and reliable level measurement. The variety of media and application criteria demand continuous improvement in the technology, while still retaining niches for older style units utilizing methods that, through their years of reliable service, inspire confidence in operators.

Here is a synopsis of the available technologies for instruments providing continuous liquid level measurement. All are generally available in the form of transmitters with 4-20 mA output signals, and most are provided with additional outputs and communications. What is notably not covered here are level switches or level gauges that do not deliver a continuous output signal corresponding to liquid level.

Whether considering a new installation or upgrading an existing one, it can be a good exercise to review several technologies as possible candidates for a project. None of the technologies would likely be considered the best choice for all applications. Evaluating and selecting the best fit for a project can be facilitated by reaching out to a product application specialist, sharing your applications challenges and combining your process knowledge with their product expertise to develop an effective solution.

Displacer – A displacer is essentially a float and a spring that are characterized for a particular liquid and range of surface level movement. The displacer moves in response to liquid level, changing the location of a core connected to the displacer by a stem. The core is within a linear variable differential transformer. The electrical output of the transformer changes as the core moves.

Guided Wave Radar – A radar based technology that uses a waveguide extending into the liquid. The radar signal travels through the waveguide, basically a tube. The liquid surface level creates a dielectric condition that generates a reflection. Calculations and processing of the emitted and returned signals provide a measure of distance to the liquid surface. No moving parts.

Magnetostrictive – A method employing measurement of the transit time of an electric pulse along a wire extending down an enclosed tube oriented vertically in the media. A magnetic float on the exterior of the tube moves with the liquid surface. The float’s magnetic field produces the return signal to the sensor. Processing the time from emission to return provides a measure of distance to the liquid surface.

Pulse Burst Radar - A radar based technology employing emissions in precisely timed bursts. The emission is reflectex from the liquid surface and transit time from emission to return is used to determine distance to media surface.  Not adversely impacted by changes in media conductivity, density, pressure, temperature. No moving parts.

Frequency Modulated Continuous Wave Radar – Another radar based technology that employs a radar signal that sweeps linearly across a range of frequencies. Signal processing determines distance to media surface.  Not adversely impacted by changes in media conductivity, density, pressure, temperature. No moving parts.

RF Capacitance - As media rises and falls in the tank, the amount of capacitance developed between the sensing probe and the ground reference (usually the side metal sidewall) also rises and falls. This change in capacitance is converted into a proportional 4-20 mA output signal. Requires contact between the media and the sensor, as well as a good ground reference. No moving parts.

Ultrasonic Non-Contact – Ultrasonic emission from above the liquid is reflected off the surface. The transit time between emission and return are used to calculate the distance to the liquid surface. No contact with media and no moving parts.

Differential Pressure – Pressure sensor at the bottom of a vessel measures the pressure developed by the height of the liquid in the tank. No moving parts. A variation of this method is often called a bubbler, which essentially measures hydrostatic pressure exerted on  the gas in a tube extending into the contained liquid. It has the advantage of avoiding contact between the measuring instrument parts, with the exception of the dip tube, and the subject liquid.

Laser - Probably one of the latest arrivals on the liquid level measurement scene, laser emission and return detection is used with time interval measuring to accurately determine the distance from the sensor source to the liquid surface.

Load Cell - A load cell or strain gauge can be incorporated into the support structure of the liquid containing vessel. Changes in the liquid level in the vessel are detected as distortions to the structure and converted, using tank geometry and specific gravity of the liquid.

All of these technologies have their own set of attributes which may make them more suitable to a particular range of applications. Consulting with a product specialist will help determine which technologies are the best fit for your application.


Optimizing Level Control in Combined Cycle Gas Turbine Plants

Magnetrol® International and Orion Instruments®, both recognized global innovators in level measurement technology, provide optimizing solutions for liquid level control in combined cycle gas turbine plants and other similar applications.

An overall cost analysis can reveal savings in the range of 25% to 35% through the application of the most advantageous level measurement technology. Miller Energy, Inc. has developed a short presentation and discussion regarding recent developments now available in the Magnetrol® Eclipse Line of guided wave radar level instruments.

More detail is provided on the single page document provided below. Reach out to Miller Energy and learn how your operation may benefit from the application of guided wave radar level measurement technology.



Guided Wave Radar for Hygienic Applications: Advantages Over Other Technologies

Guider Wave Radar
Guided Wave Radar
for Hygienic
Applications
Operating Principle

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel via the waveguide. The pulse is reflected when it contacts a liquid surface and the distance is then calculated.

Guided wave radar transmitters are available with a 304 stainless steel housings designed specifically for use in hygienic applications. This instrument meets the needs and requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries.
Features
  • Low dielectric measurement capability (╬Ár >_ 1.4)
  • Volumetric output
  • Quick connect/disconnect probe coupling
  • Operates in visible vapors and ignores most foams
  • IS, XP, and Non-Incendive approvals
  • Ignores coating buildup
Advantage Over Other Technologies
  • Advantage over Differential / Hydrostatic Pressure Transmitter:  Replaced by Eclipse due to setpoint shifts, blockage, leakage, installation cost & long term calibration / maintenance
  • Advantage over Magnetostrictive: Replaced by Eclipse due to setpoint shifts, turn-down and clean ability & long term calibration / maintenance.
  • Advantage over RF Capacitance: Replaced by Eclipse due to dielectric shifts, coating issues & long term calibration / maintenance.
  • Advantage over Load Cells: Eclipse is more cost effective and long term cost of ownership is lower due to long term calibration / maintenance.
  • Advantage over Ultrasonic: Replaced by Eclipse due to vapors, condensation, temperature restrictions, foaming & turbulence.
  • Advantage over Through Air Radar: Replaced by Eclipse due to performance issues on low dielectric media, short range measurement because of dead band issues in small vessels, measurement issues when using false echo rejection from internal obstructions such as agitators and spray balls, signal attenuation from turbulence, foam, condensation and spray from spray balls used during cleaning or product filling. Through air radar can have issues from variable false echoes generated when spray hits the antenna when vessel is filled from spray balls.
For more information see this Guided Wave Radar bulletin: