ANALYTICAL INSTRUMENTATION & MAINTENANCE SYSTEMS (AIMS) ISA QATAR : 90 th Seminar UTILIZATION OF LASERS IN THE FIELD OF GAS ANALYZERS Presenter: ZAHEER JUDDY
Electromagnetic Spectrum
Electromagnetic Spectrum x-rays ultraviolet Vis NIR mid -IR FIR microwave radio waves 9 10 7 10 5 10 3 10 1 10-1 10-3 10-5 10 Wavenumbers nuclear electronic vibrational rotational transitions 180 1000 25000 Wavelength in Nanometers
Traditional techniques/approach in process Gas Measurements Non-Dispersive & Dispersive Infrared Non-Dispersive & Dispersive Ultraviolet Contact type measurement Next Generations Tunable Diode Laser Absorption Spectroscopy (TDLAS)
Infrared (IR) Technology About & Challenges Very Old & First technology Suitable for only measurement of Hetro-atomic molecules Moisture interference with IR Not suitable for interfering background Gases and components Complex Sampling design with removal of moisture MUST. Increased number of consumables and spares
NDIR Photometry: AGAIN!! A complexity of optical design with lot of optics components.
Components IR analyzer: Degradation of NDIR source. Contamination of filters. Wide band width (CO2/CO) together difficulties Filters NDIR source background interference
Ultraviolet (UV) Technology Good for sulfur species H2S, SO2, COS, CS2, etc.. Few Challenges: Shorter lamp life Wide emission line widths & wide Spectral range. Contamination of filters. Moving parts Replacing the filter wheel motors. UV Optics Assembly
Filter Location Table (COS / CS 2 Measurement) Filter Position 1 2 3 4 5 6 Wavelength 258 228 404 232 280 326 Primary Measurement Sv H 2 S NDr COS SO 2 CS 2 Lamp Mn/Ni Cd Mn/Ni Mn/Ni Mn/Ni Cd
Traditional Contact type Moisture & Oxygen Measurement Moisture Measurement 1. Aluminum Oxides Response Time in minutes/hours Sensor Probe Chocking Always affected by Glycol, H2S/HCL, mercury and others Difficulties in calibration 2. QCM (Quartz Crystal Microbalance) Faster response & good for low ppm measurement Sensor killing by background corrosive gases Oxygen measurement Zirconium Oxide (ZrO2) Selective for flue gases and clean applications Affected by dust, background mist and hydrocarbon gases
Think Out Of The Box???? The only tool when you have in your hand is HAMMER, every thing around looks like NAIL.
AMETEK 5100HD PROCESS GAS ANALYZER
AMETEK Model 5100HD Overview The AMETEK 5100 series TDLAS gas analyzer is an extractive system & NON Contact type measurement All these species can be measured in variety of background gases There are two versions available. The Model 5100 is single laser, single analyte configuration. Model 5100HD is dual laser, single/multiple analyte single/dual cell configuration. Model 5100HD has dual stream capability. The unit is comprised of fully enclosed optics, electronics, sample handling and built-in verification. The unit is certified for worldwide hazardous area locations. comes with built-in verification and laser line lock as standard.
AMETEK Model 5100 Overview Gases Measured Moisture Hydrogen Sulfide Carbon Dioxide Carbon Monoxide Oxygen Methane Ammonia Hydrochloric Acid Acetylene many more coming Industries Served Natural Gas Pipeline Natural Gas Processing Refinery Chemical Petrochemical Hi Purity Gas Many more..
Why Tunable Diode Laser Spectroscopy? Non-contact measurement technique No sensor aging calibration concerns No consumables Advantage for applications with high levels of water vapor Lasers last many years before replacement is needed Low cost of ownership No interferences Extremely narrow emission line widths reduce interferences from other species
Electromagnetic Spectrum:
Wavelength modulation spectroscopy For First harmonic (1f ) detection, the detector signal is demodulated using a reference signal with a frequency equal to that (of the modulation frequency ) used to drive the laser.. For Second harmonic (2f )detection, the detector signal is demodulated using a reference signal twice that used to drive the laser..
Vibrational Spectroscopy & Lasers The absorption of infrared radiation results in unique molecular vibrations In the gas-phase samples the individual transitions between discrete vibrational states are observed when measuring with high resolution Lasers have extremely narrow emission lines; hence, they are an excellent tool to probe the unique absorptions of gas phase molecules Normal Vibration Modes for Water O O O H H H H H H 18 1 2 3
Respons e Transmissio n Current (ma) Modulation and Absorption Responses 95 90 85 80 75 70 Laser Current 65 0 0.05 0.1 0.15 0.2 0.25 1 0.8 0.6 0.4 0.2 Water Absorption Time (seconds) Modulated Laser Signal 0 1 0.8 0.6 0.4 0.2 Detector Response 759.95 Wavelength (nm) 0 0 0.05 0.1 0.15 0.2 0.25 Time (seconds)
Analyte, typical absorption line width 0.05 nm Laser scan range, typically 0.2-0.3 nm, Laser spectral line width is ca. 0.0001 nm Conventional optical filter bandwidth > 5 nm
5100 Block & flow Diagram Sample cell GRIN Lens Mirror Laser Diode Beam Splitter Photodiode Reference Cell GRIN Lens Temperature Control Current Control Photodiode ELectronics Unit
Relative Absorbance Comparison of Water and Natural Gas 1 0.8 Water vapor spectrum offset for clarity 1.854 um, 5394 cm-1 Water Vapor Natural Gas 0.6 0.4 0.2 0 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 Wavelength (nm)
Key feature of 5100 : Line-Lock By adjusting the TEC temperature, the analyzer will tune the laser to emit a specific frequency that would be absorbed by Line Locking under Laser Temperature the analytes. of 27.55 C. Reference and Sample Spectra check the peak ( line ) in the spectrum. The peak ( line ) is locked if its index is at a certain position in the spectrum, varying by a line-lock window. 0.03 0.12 2F Signal 0.02 0.01 0.00 27.4 C 26.8 C 25.5 C 25.55 C 25.54 C 2F Signal 0.08 0.04 0.00-0.04-0.01-0.08 0 50 100 150 200 Spectral Index 0 50 100 150 200 250 Spectral Index
Advantages of LASER: Precise measurement
Advantages of LASER: Precise measurement
DFB Tunable Laser Diode The Heart of it All Very Accurate!! Can be tuned to measure to the accuracy level.
Laser/Fiber Panel 5100
Reference Cell TDLAS
Verifying the Reference cell function:
Sample cell
Select Wisely: Don t Load all your application on LASERS, you need to be careful on the following. Always provide complete stream composition. Moisture and H2S in nitrogen is different than moisture and H2S in methane. Proper sampling system
COMMON ISSUES WITH SAMPLING SYSTEM 1. Sample Line Issues Longer distance??? As near as tapping point possible (less than 10 meters) 2. Probe Installation Issues 3. Big SHELTER/HVAC Issues Maintenance issues 4. Location of Tapping Points difficult to install and maintenance 5. SS 316 Electro Polished Tubes 6. Range issues for Analyzers 7. High H2S Exposure
Points considerations in Process Analyzers 33
Probe Installation Issues No heating/ Jacketing Proper Probe Heating with Jacketing
Probe selection for high pressure process line Analyzers
Probe Installation Location Difficult location for Probe installation
Heated Sample line selection & Installation Shortest length between tapping point and analyzer less than 10 meters Proper bending & Installation of sample line by AIMS
Poor Installation sample line
Sample installation Best Practices
Correct type of Heated Sample line selection Teflon: Inert but temperature limitations (dewpoint temperature), permeation Stainless Steel: welded, seamless but cleanliness and adsorption problems with some applications ElectroPolished: improved surface finish for improved absorption resistance ElectroPolished/Coated: for a product that is inert as Teflon but strong as steel Weatherproof Jacket Electric Traced Steam Traced Insulation Process Lines Steam Supply & Condensate Return Buffered High Temp Bundle CEMS Designs
Case Study 1 : ZADCO Analyzer application : ZADCO off-shore plant Service : Glycol Dehydration Unit Issue : Glycol & Liquide Carryover Played with all the traditional techniques and was failing. Aims studied the case and proposed AMETEK 5100-HD for the application. It has now been 5 years they are running smoothly.
Data Sheet
Case Study 2 : GASCO Analyzer application : Acid Gas Flare Measurement O2 in ppm : Range 0-1000ppm. H2S in the stream is 20% Analyzer is in ESD loop
Data Sheet For Case 2
Case Study 3: QP Service : Recycle Gas compressor suction Application : Moisture measurement. Process stream contains 15 ppm Chlorine (HCL). Existing : Al2O3
Data Sheet For Case 3
Case Study 4 : PDO OMAN Analyzer application : Acid Gas Flare Measurement O2 : 0-2% H2S in the stream Analyzer is in ESD loop
Installation in PDO, OMAN