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ABSTRACT
A question often raised by plants facing new air pollution monitoring requirements is whether there are proven technologies for measuring the wide range of
pollutants they are being asked to monitor and report. The only defensible answer to this question is a very strong yes. While environmental monitoring up to this time has been largely limited to a few targeted
gases like SO2 and NOX, process engineers have for years been accurately measuring the same wide range of gases environmental managers are now being asked to monitor. The combinations of
rapidly advancing technology and a need for greater automated process control have combined to allow process engineers of today to accurately monitor essentially any process variable or gas needed. This paper
defines the wide range of monitoring technologies readily available. The reliability and accuracy of these systems/technologies are supported in actual field examples. This paper provides the material necessary to
insure that plant environmental managers fully appreciate the well-documented capability of modern day instrumentation to provide whatever data is required by the plants permit. More specifically, this paper
provides the plant environmental professional with a practical path forward for selecting and installing the most cost effective air pollution monitoring technology commensurate with the specific stake, liability
and preferences of his or her site.
The Atmospheric Pollution Prevention Act
The Atmospheric Pollution Prevention Act (45) of 1965, as amended, is the primary mechanism in South Africa for the management and control of air pollution.
This legislation provides for the following:
Control of noxious and offensive processes, commonly known as Scheduled Processes, of which there are 162 listed in schedule 2 of the Act. These
processes are deemed to be subject to the practice of Best Practicable Means of pollution abatement ("BPM"). BPM is a set of guideline standards issued by the Department of Environmental Affairs and
Tourism stipulating the level of technology that is the best, practicable means of preventing or reducing to a minimum the escape of noxious or offensive gases into the atmosphere at source. These guidelines are
continually updated as new cleaner technologies are developed. The Chief Air Pollution Control Officer of the Department of Environmental Affairs and Tourism controls the application of the BPM approach.
The Department of Environmental Affairs and Tourism is currently in the process of revising the Act. Any amendments to the Act will need to be applied in
the DMA.
Analytical Instrumentation History
Analytical equipment has progressed over the years from analogue instruments born in the laboratory to new digital analytical equipment designed for
specific applications. The analyser list has grown; we can now add flame ionisation detection gas analysers (FID), gas chromatography (GC), and mass spectrometry (MS). While there are other methods in use today and
others under development, those mentioned here are the workhorse methods in process analytical chemistry and have been in everyday use, 24 hours per day, 365 days per year for making process analytical measurements.
Some gases are difficult to measure just because they are hard to detect, but in general, reactive and condensable gases such as HCl, NH3, HF and formaldehyde, present the greatest measurement challenges. Such gases
may react with other components within the stack gas stream; they may condense or be absorbed by liquid condensate within a cold extractive sampling system, they may adsorb onto surfaces, or they may polymerise
before reaching the Analyser. Thus, depending upon the components making up the flue gas stream, special sampling equipment may be needed and special operation and maintenance procedures may be required to achieve
reliable results. Thus, in addition to the measurement technologies of the instrumentation, one must also consider the technology of sample handling and transport.
A brief overview of these analytical techniques and advances in their technologies follows. Nondispersive infrared gas Analysers (NDIR) utilises several
different detection techniques. Opto-pneumatic detectors, commonly known as Luft detectors (from their inventor, Karl Luft), interference filter photometers (IFC), and gas filter correlation (GFC) are the more
predominant types. The theory of operation of these infrared methods is similar and is based upon absorption of infrared energy in the 2 to 11 micron wavelength range. Simple molecules with less than 5 or 6 atoms
have infrared absorption spectra with fine structure. Gases fitting this description are ideal for Luft and GFC types of Analysers, which correlate the spectra of the sample gas with the spectra of the pure
component of interest. Interference filter correlation is capable of measuring gases with either fine structure in the spectra or broadband absorption. Proximately 80 gases have been measured with NDIR. The
capability list of all techniques mentioned herein is based on current availability in the marketplace and not theoretical considerations. Of the 80 gases, approximately 50% of the NDIR instruments sold are for
measurement of Carbon Monoxide (CO).
NDIR SCHEMATIC
Recent developments in NDIR Analysers include the ability to have multiple optical benches in one Analyser and
stacked detectors that result in as many as four (4) gases being measured in a single instrument. Microprocessors
have added many capabilities to modern NDIR analysers, which include a platform, where a single system controller
provides the user interface for as many as 3 analytical modules. The system controller provides industry wide interfaces to control systems and common computer networks. MODBUS is included for control systems and
Ethernet is provided for interfacing to personal computers. The interference filter correlation (IFC) photometric
analysers such as the Multiwave have been enhanced through microprocessor technology to measure multiple components and also operate over Analyser networks. These Analysers have also been successfully applied to hot
wet measurement demands by heating to temperatures as high as 200 C. The IFC approach allows a spectroscopist to evaluate a complex sample matrix and select proper wavelengths of light to make successful analytical
measurements of the component of interest. These Analysers are custom built for the application. Improvements
have also been made in the calibration of NDIR gas Analysers. By using calibration cells, small optical cells with
actual test gases encapsulated within, Analyser calibration can be checked without bottles of expensive test gases.
Ultraviolet (UV) Analysers are in general more sensitive than NDIR Analysers. Another advantage of UV Analysers is that water (H2O) is transparent to UV. SO2 and NOx are frequently measured with this technology. Other
possibilities are NO2, H2S, CS2, COS, Cl2, NH3, and other gases. The UV Analyser utilises a 4 beam optical approach
so that a double quotient can be formed and removes variables such as dirty windows and ageing of components so that the result is a more robust and stable analyser.
UV Analyser Schematic
Paramagnetic Analysers are commonly used to measure oxygen, and are normally used in CEMS to measure oxygen
as the diluent gas. Newer analysers of this type are more resistant to corrosion and are smaller than their
predecessors, which result in a faster and more stable response. There are several types of paramagnetic Analysers.
The more widespread is the dumbbell type or more properly, magneto dynamic, which uses a small dumbbell shaped
optical component to physically determine the oxygen concentration. These have the limitation of having moving
parts and optical components exposed to the sample gas, which may be corrosive. Another type of paramagnetic is
the Magnetic wind or thermomagnetic type of Analyser, where there are no moving parts and the construction is of
highly corrosion resistant materials, which results in an extremely robust Analyser with a long service life. Microprocessor technology has also advanced paramagnetic Analysers by allowing for surrogate calibration
mixtures for difficult or impossible to prepare gas mixtures or very toxic mixtures.
Flame ionisation detection (FID) techniques are widely used to measure hydrocarbons. During the combustion of
organic substances, in a hydrogen flame, electrically charged particles are produced. The resulting current of these
ions is proportional to the organic carbon content. FIDs have very large dynamic ranges, from 10 to 100,000 mg of
organic carbon / cubic meter. The hydrocarbon analyser utilises a heated system from the point of the sample
interface throughout the entire analytical system to avoid cold spots where heavier hydrocarbons may be adsorbed
and cause erroneous results. Modern FID Analysers feature self-monitoring, automatic fault recognition and logging
functions. Some FID Analysers include options for a sparger, or water stripper to measure volatile organics in water.
While FIDs respond to all hydrocarbons, it may be possible to use a FID type hydrocarbon analyser to measure a hazardous air pollutant if the pollutant is a hydrocarbon and no other hydrocarbons are present.
Gas Chromatography is a very versatile analytical technique that separates the sample stream into its individual
components for measurement. The process or on-line gas chromatograph differs dramatically from its laboratory
counterpart, the only common area being the separation concepts. In current practice, designs integrate a basic
Analyser (chromatograph) with a controller & microprocessor package. These systems can perform as stand alone
units or be interfaced with multiple chromatographs, distributed control systems, or a host computer. Significant
changes have been made in valves, columns, column systems and detectors. Tough polyamide coated fused silica
columns with stabilised stationary phases have reached a high level of reliability and are routinely used in Process
Chromatographs. The most popular detectors for online chromatographs are still the thermal conductivity and flame
ionisation detectors, but other component selective detectors are being used including electron capture, flame
photometry, photoionisation, and chemiluminescence. Most gases can be measured by gas chromatography. The
basic requirements are: the compound has a sufficient vapour pressure so that it will elute through the column, a
chromatographic separation can be made, and the compound is stable thermally, i.e., does not crack at the oven
temperature. Process chromatographs have been used in CEMS when the pollutant of interest is not one of the criteria pollutants, i.e.; there is not a standard off-the-shelf solution to the analytical need.
Schematic layout of a total hydrocarbon analyser
Mass spectrometers have been a basic laboratory tool for many years. The mass spectra of a compound provide a
positive fingerprint identification of that compound. Mass spectrometers also have inherently broad chemical
applicabilities because the ionisation process is fairly uniform for all compounds. One instrument can measure many
compounds providing a cost effective means of monitoring. They are inherently fast, sensitive, and capable of a
wide dynamic range (parts per billion to 100%). The mass spectrometer is quantitative and linear since its output is
directly proportional to the concentration of the species in the sample. It is a reliable, stable and low maintenance
instrument because it is electronically based rather than chemically based, as are many single sensors. Finally, the
mass spectrometer has maximum flexibility because its broad capabilities can be selectively used under programmable microprocessor control. Recent advances in technology have been made which provide the elements
necessary for continuous online applications such as CEMS and air monitoring. These developments include: the turbo molecular vacuum pump, which allows operation in minutes, highly reliable, and low maintenance; the
quadruple filter, which provides measurement of any mass from 0-400 amu; low cost computing power, and packaging for continuous operation environments.
The mass spectrometer is used often to measure hazardous air contaminants, which require fast analysis. In
situations where many sample points are required, the speed of analysis allows a multistream-sampling concept to be
used. As many as eighty (80) port valves can be used to monitor many sample points throughout a plant or process.
Thus, the flexibility of this instrument makes it possible to monitor many different streams using several different methods for several different gases (up to 40).
Fourier Transform Infrared Analysers are another technology that has been taken from the laboratory and used
online for CEMS. The advents of inexpensive and powerful microprocessors have made this possible. One advantage of this method is that several gases can be monitored at the same time by the same instrument. Heated
versions are available that make it possible to monitor hard to handle gases like HCl and NH3 down to 10 ppm. These
units are found in applications in the monitoring of combustion sources, toxic waste incinerators, and industrial processes as well as ambient monitoring applications for hazardous air pollutants.
Basically, the FTIR is able to produce very detailed infrared spectra over a range of typically 2.5 to 25 microns
wavelength. Through the power of modern microprocessors, the spectra is calculated from an interference pattern
and matched mathematically with the sample data held in memory. A variety of algorithms have been developed to
obtain the concentration values from the wealth of data provided by this instrument. An interesting feature offered
by this technique is the storing of digital spectra, not just the calculated values. Some time later, the stored spectra
can be processed to determine concentrations of other gas components that were deemed unimportant at the time.
For example, if a process upset caused the release of gases not normally present, the spectra could be evaluated to
determine if the release actually occurred and to what extent. The operation of the FTIR system is controlled completely by the PC software, enabling the following functions:
Display of all measured results and status messages on the monitor, manual interactive operation of the system
during commissioning and servicing, remote diagnosis by modem, self-diagnosis, and archiving of measured data
and self-diagnosis data. Technology and products are available to make most measurements. The formula to the best
and most successful monitoring project is to find the most cost-effective approach that has the best workable
solution and is in the hands of the end user. Customers, suppliers, and government agencies must work together to achieve realistic and cost effective protection of our environment regardless of the methods chosen.
Some detailed examples of environmental applications directly applying some of the above technologies follow.
Example 1, (Emission)
Continuous Gas Analyser
Emission Monitoring of Air Pollinates in Recovery Boilers in Pulp and Paper Plant.
(See Analyser System Layout Drawing)
This analyser system was designed to measure SO2, CO, O2, NOx and H2S (TRS). The sampling method used is
extractive. An extractive gas analysis system operates under standard conditions. The emission gas is sampled out
of the stack with a heated probe. The sample gas lines are heated and always need to be kept at a minimum. The gas
sample enters the analyser panel via a 3-Way solenoid and an acid filter is used as protection for the sampling
system. The sample gas is cooled to 3C in the cooler. The cooler removes the water in the sample gas. The gas
sample is then pumped to the analysers via a sample pump. The analysers can handle a max of 60l/h and a pressure below 10 Kpa. The sample system has to be designed with these limitations in mind.
The SO2, CO and O2 will be analysed using a NDIR analyser with two measuring benches, one for SO2 and the other
for CO. The O2 is measured with an electrochemical cell. A UV Analyser is used to measure the TRS and the NOx.
The H2S and mercaptans is converted to SO2 and reported as TRS (total reduced sulphur). The SO2 in the sample
gas is dosed out with 3% H2O2 in the sample gas cooler.
a) Mercaptan + x O2 = yCO2 + z SO2 + nH2O
b) H2S + 3/2 O2 = SO2 + H2O
The reaction takes place at 800oC in the presence of oxygen. The flow must be 60l/h and the sulphur components needs to be < 1000 ppm.
NOx measured as NO
NO2ºNO
The reaction takes place at 800C with the aid of LF 316 Catalyst. The flow must be 60l/h and the NO2 concentration has to be between 100-3000 ppm.
Example 2, (Emission)
Stack Monitoring by FTIR
Analytical process instrumentation with a modular system concept
Advance Cemas emission monitor
Higher demands and stricter limitations in environmental protection require the continuous measurement of a
growing number of pollutants that are emitted in lower and lower concentrations. To meet these demands of
environmental protection the effects of processes have to be monitored exactly. Consequently, reliable instruments
for gas analysis are important to realise the analytical requirements and demands. However, the instruments alone
are not sufficient. Another essential part of the analysis system is an adequate sampling and sample conditioning
unit as well as the integration into the measuring and control system as a whole. A comprehensive know-how is absolutely necessary because of the individuality of the different measuring tasks. Not everyone has this
specialised know-how. Therefore, a partner is needed providing services which considerably exceed the mere delivery of high-quality, powerful instruments but include advisory service to users, engineering, system
engineering, assembly, commissioning and training as well as after-sales service.
System Concepts
Based on proved standard modules, customised solutions are provided including sample conditioning, Analysers,
system control as well as analysis systems ready for measurement, which have been tested for their intended
applications. Due to the worldwide presence of ABB, systems are in accordance with different regional requirements.
The analysis systems can be integrated into already existing systems or be delivered as complete system solutions,
e.g. with integrated data management. With Advance Cemas, two multi-component measuring systems are offered for emission monitoring and process control based on different measuring principles: Advance Cemas- NDIR is
based on Advance Optima, a system for process analysis. The infrared Analyser Uras 14, the oxygen Analyser Magnos 16 or the electrochemical oxygen sensor is used. The Uras 14 is capable of measuring some 50 to 60
different gas components.
CEMAS FTIR system
CEMAS FTIR components
The CEMAS FTIR is based on the spectrometer MB 9100. It provides the high selectivity of the FTIR-technology
and additional infrared components can easily be added if needed. The analysis system is used especially for the measurement of components like HCl, HF, NH3 or H2O that require hot & wet measurements. The measurement of
O2 and THC can be integrated as well. Analysis systems must be serviced regularly to minimise failures and to
increase life expectancy. The Analysers are measuring several components simultaneously. Advance Cemas-NDIR measures up to four gas components, e.g. CO, SO2, NO and O2, Advance Cemas-FTIR up to eight gas components,
in individual cases even more. Furthermore, the analysis system Advance Cemas contains all components necessary
for gas feed and conditioning, such as the cooler module with integrated gas feed unit. Due to the compact design of
the systems especially short sample gas lines can be used and the number of connections minimised considerably. The simplified spare-parts stocking by using standard modules also results in a cost reduction.
Calibration concepts - convincing and cost-effective
Analysers have to be calibrated in certain intervals to ensure their accuracy and stability. The test gases and system
components used for this calibration contribute considerably to the investment and operating costs. With the
analysis system Advance Cemas-NDIR, can calibrate without test gases. The zero point or span point respectively
for the oxygen measurement as well as the zero point for the infrared measurement is adjusted with ambient air. The
span adjustment for oxygen measurement with the infrared Analyser Uras 14 are made by means of gas-filled,
patented calibration cells. A long-time test over six years has proved the stability of these calibration cells. The
calibration without test gases is run automatically. Due to its high stability the calibration costs of the Advance
Cemas-FTIR are low. All instrument dependent factors are taken into consideration through the daily registration of
the reference spectrum with zero gas. Because of this automatic zero point adjustment and the measuring principle, a
calibration of zero and reference point every six months is sufficient to ensure smallest measuring ranges. The storage of test gas is not necessary. A calibration check with test gas can be carried out twice a year.
Everything under control
Usually, systems for emission monitoring are not installed at convenient locations. Therefore, normally an
inspection on-site is required in regular intervals. Furthermore, you have to go to the analysis system to operate it.
This is different with Advance Cemas; additional sensors in the Analyser and in the components for sample conditioning provide the status information centrally. Thus the gas flow is supervised, a condensate drain is
recognised early, a message is displayed that the condensate bottle has to be emptied, or the complete optics is
checked. Failures and frequent inspections can be avoided. All information is integrated into the status messages
failure or maintenance required of the Analyser. Via the Ethernet interface detailed information can be obtained from
a PC, e.g. in the control room, a diagnosis can be made or the Analyser can be remotely operated. Remote control becomes reality.
Advance Cemas-FTIR System Description
Measurement principle
The Advance Cemas FTIR is a multi-component emission monitoring system for simultaneously measuring HCl, HF, NH3, CO, NO, NO2, SO2, H2O, CO2 , O2 and total hydrocarbons. The infra-red-active measurement components are
measured at high temperature (180oC) using an FTIR spectrometer (FTIR = Fourier Transform Infra Red). The O2
measurement is performed using an electrochemical oxygen sensor. The hydrocarbon content is measured using a flame ionisation detector (FID), when required.
Mode of operation
(See Figure below)
The sample gas is piped via the heated sampling filter (2) and the heated sampling pipe (4) to the heated sample-gas feed (5)
. The heated cell of the FTIR spectrometer (11) protrudes directly into the heated sample-gas feed. Behind the gas outlet of the cell and FID (12)
can be connected for measuring hydrocarbons within the sample-gas feed. A proportion of the sample gas stream is piped to the oxygen Analyser (13) from the heated sample-gas feed. Through the check valve
(3) on the sampling filter (2) dry compressed air is released automatically in the event of any problem
, e.g. if the temperature falls below the permitted level in one of the heating circuits. The system is also purged of sample gas to avoid condensation. Through the second check valve (10) dry, CO2-free compressed air is
automatically released for the purpose of recording zero-gas spectra. The molecular sieve unit (14) is used for conditioning the compressed air, i.e. drying it and reducing its CO2 content.
CEMAS FTIR system design
Sampling system
The sampling system comprises:
The probe tube, the filter device, and the sampling pipe
Probe tube
The probe tube (1) is made from special steel (316T) and can be supplied in either an unheated (probe 40) or a heated
version (probe 42) and in lengths 1 m, 1.5 m and 2 m. A heated probe tube is only necessary in exceptional cases (e.g. cold bridge on the flange).
Filter device
The PFE2 filter device (2) contains a coarse filter (20 mm) that is heated to 180 C. The sampling pipe is connected
directly to the filter device. For emergency purging of the entire sample-gas path from the inlet via the sample cell up to the outlet, cleaned compressed air is released through a heated check valve (3)
on the filter device. For external installation of the sampling probe an optional protective probe case can be supplied. For situations with a high dust
content a purging facility can be supplied for periodic cleaning of the coarse filter.
Sample Line
The sample line (4) can be heated to 180 C by a built-in fixed-resistance thermistor (90 W/m). The temperature is
monitored using a Pt-100 sensor. The sample gas is transported in a PTFE hose (8 x 6 x 1mm). In order to avoid a long dead time the sample line should be no longer than 40 m.
Feeding and conditioning of sample gas
Sample-gas feed
The sample-gas feed comprises:
The needle valve, the sample-gas feed pump, the fine filter, the flow monitor, and the check valve for releasing zero
gas and test gas. The sample-gas feed is housed in a heated cabinet.
Needle valve
The needle valve (6) is used for adjusting the sample-gas flow during commissioning of the measuring system.
Sample-gas feed pump
The motor for the sample-gas feed pump (7) is attached on rubber mounts to the right-hand side panel of the
warming cabinet. The entire top of the diaphragm pump protrudes into the warming cabinet.
Fine filter
The ceramic fine filter (8) serves to separate out the finest particles. It has an average porosity of 0.05 m.
Flow monitor
The flow monitor (9) is based on a Reed contact with a magnetic piston seated in PTFE. The lower switching point is
set to 250 l/h. If flow falls below this rate, the status signal Fault is output.
Check valve
Through a check valve (10) between the pump and the fine filter both zero gas and test gas can be released. An
external magnetic valve controls this valve. An opening pressure of 10 psi (= 0.7 bar) is required.
Heated cabinet
The cabinet is heated to 180oC to prevent the temperature from falling below the dew point. An external temperature
controller handles temperature control with a Pt-100 temperature sensor in the warming cabinet. For connecting the
heated lines, mounting flanges are fitted on the left and right side panels of the heated cabinet in such a way that no
cold bridge can develop. The internal piping in the sample-gas feed is in 6 x 4 x 1 mm PTFE. Transition pieces are made from special steel as Swagelok connections.
FTIR spectrometer
(See Figure below)
Spectrometer layout
The FTIR spectrometer, model MB9100, is installed suspended in the system cabinet. Its main components are as
follows: The interferometer with the electronics for controlling the spectrometer and communicating with an external computer, the IR-ray source, the transfer optics and the IR detector, and the cell.
Interferometer
The interferometer modulates the IR light along with the light from the laser and from the white-light source. The
latter two are used for scaling the spectrum. The complete interferometer unit comprises the above light sources,
their power supplies, the detectors for laser light and white light, the beam splitter, the retroreflectors, the transfer
mirrors and the interferometer arm. The interferometer arm is distinguished by its twin-pendulum design, which contributes to the spectrometers robustness and freedom from over sensitivity.
IR-radiation source
The source of the IR radiation is a glowbar, a resistor with positive temperature characteristics, made from silicon carbide.
IR detector
The IR detector is a DTGS detector (deuterized triglyceride sulphate).
Cell
Connected to the spectrometer is the heated long-path cell. Via an optical transfer device located above the cell, the
IR ray passes into the cell. In the cell, it is reflected several times by three mirrors, increasing the length of the optical
path before leaving the cell again and arriving at the detector. The optical path length is fixed in the factory through the setting of the mirrors. It is normally 6.4 m.
Processing of measured values
The digitised detector signal is evaluated in terms of concentration of the different sample-gas components by a
computer that forms one of the system components.
Oxygen Analyser Sample-gas feed
A proportion of the sample gas stream is diverted and piped to the oxygen Analyser from the sample-gas feed. To
prevent condensation the sample gas is passed along the heated cell and into the oxygen analyser.
Oxygen sensor
The type KE-25 electrochemical oxygen sensor in the oxygen analyser operates on the same principle as a lead acid
battery. The cathode of the electrochemical cell is made of gold and the anode of lead. A weak acid is used as an
electrolyte. At the cathode, the oxygen entering from the sample gas, is absorbed electrochemically; a process
through which electrons are used up. At the anode, lead releases electrons and is oxidised to form lead oxide. The
current flowing through the outer circuit in this process is proportional to the diffusing oxygen. A porous barrier
limits the diffusion from the gas phase so that a linear signal results corresponding to the concentration of oxygen.
The surface of the lead anode regenerates itself continuously as the lead oxide dissolves in the electrolyte.
Removal of condensate
In order to remove the condensate, the sample gas is passed over a condensate trap. The condensate is expelled
from the filter housing by means of a peristaltic pump.
Flow monitoring
Monitoring the flow upstream of the oxygen sensor ensures a minimum flow of 10 l/h. If the flow rate falls below this
value, then a status signal Fault is output.
Discharge of the condensation heat
The condensation heat is discharged through the cooling device in the system cabinet. For this purpose, a cold-air
pipe passes from the cooling device into the oxygen Analyser.
Processing of measured values
The analogue sensor signal is digitised, incorporated into the processing of measured values from the Advance
Cemas FTIR, and displayed on the screen. The measured value for oxygen, common with all other measured values, relates to the moist flue gas.
Adjustment
The oxygen Analyser is automatically adjusted during the daily recording of the zero spectrum.
System design
System cabinet
All components of the system are housed in a system cabinet. In the upper, cooled section are the FTIR
spectrometer, computer, control system and analogue outputs, temperature controller, and as an option the O2 Analyser.
Located in the lower section of the cabinet is the heated sample-gas feed.
Control and monitoring of temperature
All the heated circuits, i.e. filter system, sample line, sample-gas feed and sample cell in the FTIR spectrometer are regulated and monitored to 18oC. If the temperature falls below this level, a Fault status signal is output and the
complete sample-gas path is purged with dry air via the filter apparatus.
Operation, display and data output
During commissioning, shutting down or maintenance tasks the system is operated via a menu-driven user interface
displayed on a PC monitor. A PC keyboard enables operations to be controlled, parameters to be set and the menu to
be modified. All measured data is displayed on the screen in the units requested, as well as output in the form of analogue signals (420 mA). All measured values relate to moist sample gas.
Example 3, (Process)
Tasks for the Process Gas Analysis
Cement Industry
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Measuring Task
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Measuring Component
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Fire-Optimisation
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CO - O2
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Thermal Optimisation
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NO
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Safety
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CO - O2
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Coal Fire Power Plants Industry
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Measuring Task
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Measuring Component
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Fire-Optimisation
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CO - O2
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Fire Monitoring
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CO - NO - CO2 - O2
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DENOX Efficiency
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NO
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E Filter Monitoring
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CO - O2
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Milk of Lime Dosing
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SO2
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Flue Gas Desulphurisation Efficiency
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SO2 - O2
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Iron and Steel Industry
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Measuring Task
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Measuring Component
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Blast Furnace gas
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CO - H2O - CO2 - H2 CH4 - N2
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Coke Oven Gas
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NH3 NO - H2S
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Conclusion
It is proven that process engineers, in all the different industry sectors have for years been measuring the same wide
range of components that Environmental Managers are now being asked to monitor. The key to successful environmental monitoring systems is to design a simple, easy to maintain, accurate and reliable analysis system.
This paper has shown that the technology is available. It is now for the Environmental Managers to insure the correct implementation thereof.
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