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CODEL International Ltd Station Road, Bakewell, Derbyshire DE45 1GE England Tel : +44 (0) 1629 814 351 Fax : +44 (0) 8700 566 307 e-mail : sales@codel.co.uk website : www.codel.co.uk. Total Solutions - Total Confidence. CODEL. Continuous Emissions Monitoring. CODEL.
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CODEL International Ltd Station Road, Bakewell, Derbyshire DE45 1GE England Tel : +44 (0) 1629 814 351 Fax : +44 (0) 8700 566 307 e-mail : sales@codel.co.uk website : www.codel.co.uk Total Solutions - Total Confidence CODEL
Measurement of all pollutant gases Measurement of solids emissions Measurement of complementary parameters Measurement to comply with legislation Secure data presentation Maximum reliability Low cost of ownership Customer requirements for continuous emissions monitoring CODEL
CODEL SmartCEM • Fully integrated system • Seven gas species in a single analyser • Particulate measurement • Pollutant gas flow measurement • Automatic data normalisation • Five-year data logging & reporting • Automatic calibration verification CODEL
Gaseous species • Carbon monoxide CO • Nitric oxide NO • Nitrogen dioxide NO2 • Sulphur dioxide SO2 • Hydrogen chloride HCl • Methane CH4 • Carbon dioxide CO2 • Water vapour H2O CODEL
Available techniques for continuous gas analysis • Infrared spectroscopy • Ultraviolet spectroscopy • Electrochemical cell • Solid electrolyte cell • Paramagnetic • Tuneable diode laser • Chemiluminescence • Flame ionisation devices CODEL
wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CO NO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species SO2 CO NO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species SO2 CO2 CO NO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CH4 SO2 CO2 CO NO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species CH4 HCl SO2 CO2 CO NO CODEL
H2O H2O and CO2 wavenumber = 1/wavelength in cm = 10000/wavelength in μm Infrared spectroscopy Suitable for measuring many different species NO2 CH4 HCl SO2 CO2 CO NO CODEL
wavenumber = 1/wavelength in cm = 10000/wavelength in μm Carbon Monoxide CO CODEL
Live and Reference measurements It is necessary to separate the infrared energy absorbed by the measured gas from the energy modified by other effects such as: • Particles in the gas • Variations in the transmitted energy • Contaminated optical surfaces CODEL
Multiple measurements in a single analyser infrared detector Pairs of live and reference optical filters are positioned sequentially in front of the detector
Multiple measurements in a single analyser infrared detector Pairs of live and reference optical filters are positioned sequentially in front of the detector
Multiple measurements in a single analyser infrared detector Pairs of live and reference optical filters are positioned sequentially in front of the detector
Multiple measurements in a single analyser infrared detector Pairs of live and reference optical filters are positioned sequentially in front of the detector
Application of IR spectroscopy • Conventional cold extractive • Conventional hot extractive • Extractive with permeation dryer • Open path cross-duct • In-situ diffusion probe • Heavy duty hot extractive CODEL
Conventional cold extractive • Simple probe with pre-filters • Condensate removed at probe • Simple sample lines • Some gases are absorbed in the condensate • Long sample lines can freeze • Major maintenance required if any water or solids reach the delicate analysers CO NO NO2 SO2 Dryers & filters Condensate drain Free-standing analyser cabinet in control room CODEL
Conventional hot extractive • Heated probe with pre-filters • Gases held above dewpoint in heated sample line • Analyser cabinet must be in control room with long expensive sample lines • Major maintenance required if heated sample lines fail and any water or solids reach the delicate analysers CO NO NO2 SO2 Final filters Free-standing analyser cabinet in control room CODEL
Extractive with permeation dryer Wet air out • Probe with pre-filter and integral permeation dryer • Water vapour removed at probe • Simple sample lines • Requires clean compressed air dried to -20degC • Major maintenance if water or solids reach the analysers • No water vapour measurement for normalisation CO NO NO2 SO2 Final filters Dry air in CODEL
Tx Rx Open path cross-duct • Simple installation • No corruption of gases • Single or multiple species • Performance cannot be audited against test gases • Performance depends on available measurement path • Variations in dust level and optical alignment can limit measurement sensitivity CODEL
Tx Rx CODEL in-situ diffusion probe • Filtered measurement chamber suitable for high dust levels • Simple installation • No corruption of gases • Single or multiple species plus H2O • Performance can be audited against test gases • Fixed optical alignment • Maximum reliability CODEL
CODEL heavy duty hot extractive • In-duct probe with pre-filter • Gases held above dewpoint in heated sample line • Multiple species plus H2O • Performance can be audited against test gases • Robust folded beam analyser requires minimal pre-conditioning • Increased measurement sensitivity • Maximum reliability Free-standing field-mounted analyser CODEL
Particulate measurement Particles emitted from a combustion process include smoke, soot, ash & carried-over process materials (such as cement). All of these particles are visible. They can be measured by looking at how much they absorb and scatter visible light. CODEL
Particulate legislation Requirements for expressing the amount of solids emitted from a process can vary dramatically for different processes and in different countries • Ringelmann number • Opacity • Smoke density • Extinction • Dust density in mg/m3 CODEL
Ringelmann A simple manual assessment of the appearance of the plume against a standard chart graded white to black in 6 steps (Ringelmann 0 – 5) CODEL
Received energy Ir Transmitted energy Io Continuous measurements For continuous measurement the energy absorbed and scattered by the particles inside the exhaust duct can be expressed as: Transmittance T = Ir/Io CODEL
Received energy Ir Transmitted energy Io Opacity/Smoke density This is the simplest continuous measurement. It is the opposite of transmittance expressed as a percentage. %opacity = (1-T)x100 This is the measurement preferred by US EPA CODEL
Opacity With a uniform dust concentration the opacity measured depends on the measured path. % opacity % opacity % opacity CODEL
Continuous dust monitoring techniques • Single pass transmissometer • Double pass transmissometer • Double beam transmissometer • Optical scatter • Triboelectric probe CODEL
Single pass transmissometer Beam splitter Measurement detector Light source Control detector • Simple low cost technique • High efficiency air purges to keep windows clean • Cannot differentiate between gas-borne particles and window contamination • Cannot detect misalignment errors CODEL
Double pass transmissometer Zero point reflector Mirror Auto-collimating reflector Light source Detector • Air purges to keep windows clean • Zero check reflector in transceiver unit • Window contamination check on transceiver only • Non-linear due to back scatter from the particles • Cannot detect misalignment errors CODEL
Double beam transmissometer - measuring Rotary valve with integral mirror Beam splitter Mirror Light source Detector • High efficiency air purges keep windows clean • Alternate, bi-directional measurement provides automatic misalignment check • Measures across entire duct section CODEL
Double beam transmissometer - contamination check Mirror rotated into optical path Beam splitter Mirror Light source Detector • Protected mirrors check individual contamination on both transceivers • Rotary valves protect transceivers during purge air or power failure CODEL
Light source Detector Back, forward or side scatter Measures light reflected from illuminated particles • High sensitivity • Can be built into a probe • Measures in a very small zone – local to duct wall • Measured zone not consistently representative • In-duct reflections cause zero errors • Unsuitable for large ducts or high levels CODEL
Triboelectric probe Measures electrical charge transfer as particles collide with the probe • Simple low cost probe • High sensitivity • Easy to install • Highly cross-sensitive to many operating parameters • Measurement is flow-dependent • Unsuitable for large ducts CODEL
Hot gas velocity measurement techniques • Pitot tube • Thermal anemometer • Bi-directional ultrasonic • Triboelectric correlation • Infrared correlation CODEL
Pitot tube Measures the velocity pressure produced at an orifice facing into the flow. Static pressure • Simple manual technique • Single or multi-point • Automated systems are prone to blockage • Unsuitable for irregular, cyclonic or angular flow • Unsuitable with high level particulates or aerosols • Complex installation Differential pressure Velocity pressure Type ‘L’ Pitot tube CODEL
Thermal anemometer Flue gases cool a hot wire held in the gas stream. The amount of cooling is a function of the gas temperature, gas composition and velocity. • Simple installation • Single or multi-point • Unsuitable for ducts with high spatial variations • Affected by condensates and dust build-up • Non-linear outputs need site calibration CODEL
Bi-directional ultrasonic Measures the difference between the transit time of sonic pulses transmitted upstream and downstream • Average measurement across entire duct • Transceivers must be purged to keep them cool and clean • Complex install and service – especially on large ducts • Complex end effects • Errors due to secondary reflections and vibration CODEL
Correlation velocity measurement Measures the offset (equal to the transit time T) between signals from 2 separated detectors. Τ Τ time CODEL
Triboelectric correlation Measures the transit time between signals from two close-coupled triboelectric probes • Simple installation • Unsuitable for ducts with high spatial variations • Affected by condensates and dust build-up • Unsuitable for turbulent flow • Unsuitable for large ducts • Close-coupled probes prone to bridging with high dust burdens CODEL
Infrared correlation Measures the transit time between signals from two separated bulk infrared detectors • Simple installation • Average across entire duct • Suitable for high temperatures • High efficiency air purges • Unaffected by condensates and dust build-up • Suitable for turbulent flow • Suitable for large or small ducts CODEL