Total Solutions - Total Confidence

Total Solutions - Total Confidence
CODEL International Ltd Station Road, Bakewell, Derbyshire DE45 1GE England Tel : +44 (0) Fax : +44 (0) website : Total Solutions - Total Confidence CODEL

Continuous Emissions Monitoring
CODEL

Customer requirements for continuous emissions monitoring
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 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 SmartCEM is the ultimate solution for continuous monitoring of flue gas emissions. It is a fully integrated monitoring concept from the basic analysers and their calibration verification packages through to digital communications, data logging and automatic reporting. At the heart of this concept is the SmartCEM station which contains all the analysers and monitors to provide comprehensive stack emission monitoring. The SmartCEM Station Control Unit (SCU) provides power to and communicates with the analysers and monitors within that station. Data from up to 32 SmartCEM stations is transmitted via a serial digital link (CODEL SmartBUS) to the Central Data Controller where it is logged on a dedicated pc or assembled for onward transmission to a plant computer or DCS. The dedicated SmartCEM system computer can be equipped with CODEL Integrated Emissions Monitoring (IEM) software and a modem link so that system operation can be monitored at all times remotely at the CODEL Customer Support Centre. In this way the expertise of the CODEL design and support teams can be quickly utilised to check that the system is operating correctly. 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

Infrared spectroscopy
Suitable for measuring many different species CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species CO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species SO2 CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species SO2 CO2 CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species CH4 SO2 CO2 CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species CH4 HCl SO2 CO2 CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Suitable for measuring many different species NO2 CH4 HCl SO2 CO2 CO NO H2O and CO2 H2O CODEL wavenumber = 1/wavelength in cm = 10000/wavelength in μm

Carbon Monoxide CO CODEL
wavenumber = 1/wavelength in cm = 10000/wavelength in μm

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

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

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 Tx Rx CODEL

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 Tx Rx CODEL

CODEL G-CEM4000 gas analyser
Infrared absorption technology The GCEM4000 analyser is designed for continuous emissions monitoring in flue gases. It consists of an infrared transceiver which projects a beam of infrared energy down a probe inserted into the flue gas and measures the energy reflected from a mirror at the end of the probe. Analysis of this energy enables up to 7 gas species to be monitored simultaneously. In-situ probe measurement The insertion probe contains a diffusion cell. An array of stainless steel sintered filters in the wall of the cell enables flue gas to quickly diffuse into the cell, while the solids in the gas stream are prevented from entering the cell by the sintered filters. This guarantees that measurements are always made on clean gases. Because the gas passes through the filters by diffusion and not by suction the filters do not become blocked by the solids in the gas stream and the probe requires no routine maintenance. The probe is capable of operating continuously at dust loadings in excess 1 gr/m3 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

CODEL G-CEM4100 gas analyser

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

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 Transmitted energy Io Received energy Ir CODEL

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 Transmitted energy Io Received energy Ir 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 Auto-collimating reflector
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

Back, forward or side scatter
Measures light reflected from illuminated particles Light source Detector 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

Differential pressure
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

CODEL V-CEM 5000 flow monitor
Many authorities now demand a report of the total annual mass of pollutants released to atmosphere per annum and rates of emission (in kg/hour or tonnes per annum) can only be calculated by measuring the concentration of each pollutant as it exists within the duct (i.e. wet and at temperature) and measuring the actual rate of pollutant flow (also wet and at temperature). It is interesting to note that many sampling analysers remove the water vapour prior to analysis to provide a measurement on a ‘dry gas’ basis (as required for compliance with some legislation). Unfortunately, without a knowledge of the water vapour dilution in the waste gas, it is impossible to calculate the in-duct concentration of each pollutant and therefore impossible to compute the total rate of emission in mg/s, kg/h or tonnes per annum. Using mg/Nm3 is incorrect and can grossly overestimate the total pollutant release. Because CODEL in-situ analysers actually measure the water vapour, they can provide measurements in both ‘wet’ and ‘dry’ formats for compliance with all aspects of the legislation. The hostile nature of the flue gas from fossil-fuel fired combustion processes makes flow measurement difficult. Manual or automatic Pitot tubes can provide a form of measurement for a short duration, but for reliable, continuous flue gas flow measurement, only non-contact techniques should be considered. A common technique for non-contact flue gas flow measurement is to use a pair of ultrasonic transceivers (i.e. combined transmitters and receivers) set diagonally across a section of the ductwork. Each transceiver transmits and receives sonic messages out of phase with its opposing transceiver and the difference between the time taken for an upstream and a downstream sonic message is a function of the flue gas flow. Where the flow is perfectly laminar, this cross-duct ultrasonic can be successful - unfortunately, perfectly laminar flow is unattainable on combustion plant. In practice there is always some turbulence. Because cross-duct ultrasonic measurement is made across a diagonal axis, local variations in flow along the direction of that diagonal axis (caused by the turbulent eddies) can produce significant errors in measurement. In practice, where emissions trading is common, many users have fitted two complete sets of sensors in an attempt to minimise these unacceptable errors. The CODEL VCEM5000 Flow Monitor utilises an infra-red correlation technique which requires no contact with the flue gases. The method resembles flow measurement with chemical dye or radioactive tracers, where the velocity is derived from the transport time of the tracer between two measuring points which are a known distance apart. However, instead of an artificial tracer being added, the naturally occurring fluctuations of the infrared energy in the gas stream are used as the tracer. Its measurement is independent from the turbulence found in the exhaust ducts from combustion processes. During trials in the USA, the CODEL VCEM5000 flow monitor was shown to continuously match the performance of a fully maintained 5-hole Pitot on a power plant, whereas other techniques involved with the trial (twin continuous cross-duct ultrasonic devices, and 3-hole Pitots) typically overestimated the flow by as much as 15% of measurement. The V-CEM5000 has been evaluated against US EPA 40 CFR 75 Subpart E Method 2F and qualifies for annual (instead of semi-annual) accuracy audits in the USA. CODEL

Data normalisation International legislation demands that any dilution at the point of measurement must be corrected. The measurement can be diluted by: Changes in temperature Changes in absolute pressure Excess air Water vapour It is necessary to measure these complementary parameters and apply the appropriate correction. This is known as normalisation Normalised values are in mg/Nm3 CODEL

Data formats With the necessary complementary measurements CODEL analysers can present data in the following formats to suit all legislative and plant requirements Particulates opacity extinction mg/m3 mg/Nm3 kg/hr Gases ppm mg/m3 mg/Nm3 kg/hr CODEL

System integration In any CEM system it is vital that normalisation and operating data are shared by all analysers. CODEL analysers are designed to communicate with each other using a series of robust bi-directional data highways. One highway distributes data between all analysers on the same stack. Another highway can be connected to a remote station for central data & diagnostic presentation and control via a PC. This central PC can be interrogated and controlled via a telephone modem or broadband internet link.

Typical CODEL SmartCEM layout
Many authorities now demand a report of the total annual mass of pollutants released to atmosphere per annum and rates of emission (in kg/hour or tonnes per annum) can only be calculated by measuring the concentration of each pollutant as it exists within the duct (i.e. wet and at temperature) and measuring the actual rate of pollutant flow (also wet and at temperature). It is interesting to note that many sampling analysers remove the water vapour prior to analysis to provide a measurement on a ‘dry gas’ basis (as required for compliance with some legislation). Unfortunately, without a knowledge of the water vapour dilution in the waste gas, it is impossible to calculate the in-duct concentration of each pollutant and therefore impossible to compute the total rate of emission in mg/s, kg/h or tonnes per annum. Using mg/Nm3 is incorrect and can grossly overestimate the total pollutant release. Because CODEL in-situ analysers actually measure the water vapour, they can provide measurements in both ‘wet’ and ‘dry’ formats for compliance with all aspects of the legislation. The hostile nature of the flue gas from fossil-fuel fired combustion processes makes flow measurement difficult. Manual or automatic Pitot tubes can provide a form of measurement for a short duration, but for reliable, continuous flue gas flow measurement, only non-contact techniques should be considered. A common technique for non-contact flue gas flow measurement is to use a pair of ultrasonic transceivers (i.e. combined transmitters and receivers) set diagonally across a section of the ductwork. Each transceiver transmits and receives sonic messages out of phase with its opposing transceiver and the difference between the time taken for an upstream and a downstream sonic message is a function of the flue gas flow. Where the flow is perfectly laminar, this cross-duct ultrasonic can be successful - unfortunately, perfectly laminar flow is unattainable on combustion plant. In practice there is always some turbulence. Because cross-duct ultrasonic measurement is made across a diagonal axis, local variations in flow along the direction of that diagonal axis (caused by the turbulent eddies) can produce significant errors in measurement. In practice, where emissions trading is common, many users have fitted two complete sets of sensors in an attempt to minimise these unacceptable errors. The CODEL VCEM5000 Flow Monitor utilises an infra-red correlation technique which requires no contact with the flue gases. The method resembles flow measurement with chemical dye or radioactive tracers, where the velocity is derived from the transport time of the tracer between two measuring points which are a known distance apart. However, instead of an artificial tracer being added, the naturally occurring fluctuations of the infrared energy in the gas stream are used as the tracer. Its measurement is independent from the turbulence found in the exhaust ducts from combustion processes. During trials in the USA, the CODEL VCEM5000 flow monitor was shown to continuously match the performance of a fully maintained 5-hole Pitot on a power plant, whereas other techniques involved with the trial (twin continuous cross-duct ultrasonic devices, and 3-hole Pitots) typically overestimated the flow by as much as 15% of measurement. The V-CEM5000 has been evaluated against US EPA 40 CFR 75 Subpart E Method 2F and qualifies for annual (instead of semi-annual) accuracy audits in the USA. CODEL

CODEL SmartCEM data logging
Measured and normalised data in many formats Real time values All data formats Digital & analogue presentation Normalisation data User-configurable spans & alarms Up to 12 channels in up to 12 groups CODEL

CODEL SmartCEM data logging
Historical data in many formats Instant access to >5yrs historical data Customised reports 3 levels of security User-configurable spans and alarms Multi-user networking System diagnostics QAL3 reporting CODEL

Total Solutions - Total Confidence
CODEL International Ltd Station Road, Bakewell, Derbyshire DE45 1GE England Tel : +44 (0) Fax : +44 (0) website : Total Solutions - Total Confidence CODEL

Total Solutions - Total Confidence

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