Optical Flow Sensing Theory Applications Training Presenter Paul

Optical Flow Sensing Theory & Applications Training Presenter: Paul Lawrence, Sr. Service Engineer Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the handouts – (specifications are on the backside of brochure pages) • Memory Key • Manuals • Cheat Sheet • This ppt Optical Scientific, Inc. – Advanced Electro-Optical Sensors

The Optical Scientific OFS 2000 Flow Meter CONTROL PANEL INPUT POWER AIRFLOW Optical Scientific, Inc. – Advanced Electro-Optical Sensors OUTPUT

Description: Correlation readout Meter Display Magnitude of the time lagged covariance function (ie Correlation or Corr), from the latest scan, is always displayed on the screen and sent to an output. Empirical studies have shown that a correlation value steadily over 100 gives a strong enough waveform shape match for accurate measurements. (i. e It can clearly “see” the eddies and they are traveling in line with the detectors. ) Optical Scientific, Inc. – Advanced Electro-Optical Sensors

How does the Optical Meter work? RECEIVER TRANSMITTER A BEAM PATH LED B FLOW AMP PREAMP DEM PREAMP ADC DIGITAL PROCESSOR AMP DEM COVARANCE PROCESSOR Vel Corr A B RS-232 OUT ADC OFS SIGNAL PROCESSOR ELECTRONICS ENCLOSURE Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Creation of shadows and the ability to “see” eddies of turbulence Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: Raw data signals Audio waveform of a single gust of air in a duct before the damper was opened Once the flow increases the scintillation in time domain looks like white noise Optical Scientific, Inc. – Advanced Electro-Optical Sensors

OFS Digital Processing an actual way the meter does it • Refractive index differences in flow create shadows on the detectors • Patterns create a waveform shape or signature (actual signal detected) • True velocity determined from time it takes signature A to show up in B • It uses the time lagged co-variance function Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Discovery & Proof of Principle Paper #1 – 1971 by NOAA Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper – 1971 by NOAA Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #1 – highlights - 1971 Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #1 – highlights - 1971 Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #1 – highlights - 1971 Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #1 – highlights - 1971 Equal weighting of the measurement over the pathlength and solving pattern (eddy) decay. Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #2 – 1977 by NOAA Dr. T. Wang went on to found Optical Scientific in 1985, and then acquired this technology and patented it. He is a Fellow of the Optical Society of America (OSA) and a Senior Member of the IEEE. Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of the history of the technology and milestones in development • Proof of Principle Paper #2 – highlights 1977 • Research showed that at shorter pathlengths and stronger turbulence, a laser scintillometer would quickly saturate and no longer “see” the signal. In addition, the calibration and pathlength sensitivity (weighting) would vary with changes in turbulence. • The use of “white light”(non-laser) and larger receiver optics solved this problem and in-addition, a differential signal processing technique was developed to cancel out the effect of vibration and electrical noise. • This opened up the opportunity for short pathlength industrial measurements (smoke and flare stack) Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Subsequent Patents given to OSI in 2002 and 2003 for the OFS EXAMPLE Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: How do we classify the OFS as a meter? BY: Methodology* BY: Installation Style Differential Producers: Orifice, Venturi, Pitot Tube, Etc. Linear Flow Meters: Turbine, Vortex, Magnetic, Ultrasonic, Optical, Positive displacement, Mass flow (Thermal, Coriolis Etc). Insertion Clamp on *Reference: Flow Measurement Engin. Handbook, Richard Miller, 1996, 3 rd Edition Pipe Section OFS is a Bolt on, using window barriers. Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: OFS System Components installations Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: Low Temperature “lift-off” – need 100 o F For Emissions applications (non-flare measurements) it has been shown that at gas temperatures below 100 deg F, the refraction / diffraction phenomena is not strong enough for stable operation (Stable Operation = Correlation values steadily over 100). Add a tracer – a small slip stream of thermal (optical) turbulence Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: Testing at NIST Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: NIST Test: OFS vs. NIST Standard Array Avg. OFS WIND SPEED (M/S) 40 30 20 10 0 0 10 20 30 NIST WIND SPEED (M/S) Optical Scientific, Inc. – Advanced Electro-Optical Sensors 40

Description: Actual velocity vs Standardized measurements Tachometer for shadows going by: We have described is the development of a meter that measures the instantaneous average velocity along a line which stretches across the pipe. It works by clocking the speed of optical shadows crossing that line. A kind-of a “tachometer for shadows going by”. It measures is the ACTUAL velocity in feet per second (Afs). If you multiply by the cross sectional area of the pipe you get actual volume in cubic feet per second (Acfs). If you want STANDARDIZED volume, you have to separately measure the temperature and pressure in the pipe and normalize the Acfs reading to standard temperature and pressure, thereby getting standard cubic feet per second (Scfs) Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Implications in the real world: Flow is messy The NIST calibration is a great demonstration of the capability of the OFS hardware, BUT it doesn’t mean you can just bolt this meter onto your pipe and expect it to read within 2%, …unless your pipe happens to also be a wind tunnel. Flow in industrial pipes deviates from perfect conditions by ‘influence quantities’* The four major ones are: velocity profile deviations, non-homogenous flow, pulsating flow and cavitation. The Flow Measurement handbook goes on to say: “Velocity profile is probably the most important (and least understood) influence quantity. The effects of swirl…and nonaxis-symetric profiles on a meter’s performance are not only difficult to analyze, but cannot easily be duplicated in the laboratory. ”* *Reference: Flow Measurement Engin. Handbook, Richard Miller, 1996, 3 rd Edition Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Implications in the real world: The well developed profile The OFS meter is used typically in larger pipes (from one foot to 30 feet or more) and in these installations it is rarer to have a well developed flow profile, simply because this doesn’t form until 10 to 20 pipe diameters from a disturbance. If you have a well developed flow profile, Great! But the odds are that you won’t in many applications. *Reference: Flow Measurement Engin. Handbook, Richard Miller, 1996, 3 rd Edition Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Implications in the real world: - Placing the beam. Plane Here you have a single of the elbow and the velocity bend velocity profile coming out B of the elbow is skewed and has an uneven structure. If your OFS light beam is in the direction of A , A perpendicular to the plane of the bend, then your measurement beam will catch an area that doesn’t vary proportionately with load. If you shoot in the plane of the bend, B it will *Reference: Flow Measurement Engin. Handbook, Richard Miller, 1996, vary with load. 3 Edition rd Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Example of measuring in a single crosssection of the velocity profile Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Decision Tree for Applying the OFS Meter Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Implications in the real world: - Five rules of Installation #1 Intersect the skewed (and load varying) structure of the velocity profile by locating the beam in the plane of the bend (disturbance). #2 The pipe must be full of flowing gas/air (it only “sees” flowing gas) #3 The flow direction must be the same as the detector alignment (within +/- 20%) #4 Be very careful of being close to control elements like dampers, which create an explosively turbulent environment upstream and downstream, at certain opening positions. #5 Be very careful of pipes which carry the shared flow from multiple, undifferentiated, load sources, because then the profile may move sideways in one direction with one of the loads, and in a different direction the other load. Optical Scientific, Inc. –with Advanced Electro-Optical Sensors

Review of different real world applications: Stability Linearity Flare applications Combustion Air Loop Close proximity to a damper Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Stability Two meters - Nine years without any adjustment Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Linearity with known strong cyclonic flow Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Flare applications Baseline Zoom fps 24 inch line Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Combustion Air Loop 3 second response time Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Example of Combustion Air Control loop measurements Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Close proximity to a damper and excessive turbulence OFS one diameter away from damper Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Review of different real world applications: Very High Temperature Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Many Varied Industrial Flow metering applications: • Stacks • Ducts • Combusti on Air • • After Wet scrubbers Flare stacks and lines • High Temperat ure • Cyclonic Flow Problems • • Positive or negative pressure Odd shapes • Tight space and small footprint • On existing angled ports • Very long paths (distances ) Optical Scientific, Inc. – Advanced Electro-Optical Sensors

A review of the great variation in flow applications that have been tackled by the OFS: ……A Flow meter that can be used in many different applications is a big advantage Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Example of saturated gas measurement Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Ducts Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Examples Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Flares Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Flares Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: Flare installation Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Description: Flare installation Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Advantageous Flow Meter Characteristics • Measurement is an instantaneous cross-stack line average • • • A single Velocity profile cross-section is measured • • • Do not need a well developed flow profile. Can be used in low pipe diameter applications (where meter is near a disturbance) Ensures a good “Flow to Load” relationship No insertion • • • More representative than a single point or a few discrete points Easier to locate because it integrates many points and smoothes out velocity profile variability No “caking”, deposits or maintenance Does not create a pressure drop that disturbs critical processes No moving parts – solid state – high MTBF • Stable measuring drift Optical technology. Scientific, Inc. – Doesn’t Advanced Electro-Optical Sensors

Example of point measurement and dirt build-up in inserted probe Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Example of backpressure with Venturi aerofoils in Combustion Air measurements Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Advantageous Flow Meter Characteristics 1. Not dependent on, or affected by, gas composition 1. 2. Extreme temperature range (very low to very high) 1. 3. Many applications can be handled with the one meter Wide measuring range 1. 4. Changes of gas composition have no affect Gases can also be saturated with water Many applications can be handled with the one meter. (0. 03 to 100 m/s) Compliant 1. 2. Compliant with EPA 40 CFR, SCAQMD (Rule 1118), API 14. 10 NIST traceable, Certified as a reference method for EPA J & Optical Scientific, Inc. – Advanced Electro-Optical Sensors Ja

Varying gas composition – example from Air Separation Plant Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Possible difficulties : • Wall affects – an issue with all meters • • Turbulence along the wall can cause interference but can be solved by two methods: Purging and Nozzle extension. Low Optical Signal Strength – a unique issue to the optical flow meter • • Cold air can have low optical signal strength and therefore the meter can suffer lower accuracy. Solved by an activator accessory – a heater stick placed upstream. Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Example of wall affects and solving the problem Optical Scientific, Inc. – Advanced Electro-Optical Sensors

The Optical Scientific OFS 2000 Flow Meter Ports CONTROL PANEL INPUT POWER AIRFLOW Optical Scientific, Inc. – Advanced Electro-Optical Sensors OUTPUT

Example of wall affects and solving the problem Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Low Optical Strength and solving the problem Optical Scientific, Inc. – Advanced Electro-Optical Sensors

X-proof activator Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Flare meter zero bounce – Pressure Hammer Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Strengths & Weaknesses: Optical Scientific, Inc. – Advanced Electro-Optical Sensors

Optical Flow Sensing Theory & Applications Training Thank you for your time! Optical Scientific, Inc. – Advanced Electro-Optical Sensors