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Über dieses Buch

Developed from a short course taught at Leeds University, this book covers methods of monitoring emissions of air pollutants from stationary sources. It surveys the techniques and points out their advantages and disadvantages.



1. Legislation on emissions of air pollutants and their monitoring

This book is concerned with the monitoring of the emissions of air pollutants into the atmosphere from industrial processes. The reason why this topic has become such an important one in many countries is that there is an increasing weight of legislation requiring operators to provide information about gaseous and particulate substances which are released into the environment from the processes they control. The concerns which lie behind the legislation may relate to
  • human health effects of pollutants;
  • potential damage to other aspects of the environment (for example acid rain and ozone generation with their consequent effects, or building decay);
  • amenity issues (for example black smoke or visibility degradation); or
  • global issues such as climate change.
Andrew G. Clarke

2. Gas composition calculations

Without Abstract
Bernard M. Gibbs

3. Particulate emissions by extractive sampling

In contrast to the measurement of gaseous emissions which can be routinely undertaken with an accuracy of a few percent, the measurement of particulate emissions is far more difficult. This arises primarily from the maldistribution of particle concentration within the duct or chimney coupled to the non-uniformity of the gas velocity. It is also partly due to sampling difficulties. Variations in the particle concentration from point to point within a duct or flue may arise for several reasons. These include incomplete mixing downstream of a junction if the two gas streams bear different particle loads, or incomplete mixing downstream of a point where air has leaked into the process gas stream. Since the air is likely to be relatively cool this problem should be detected during the preliminary probing of the gas temperature which is a normal part of the testing procedure. It may then be necessary to seal the leak or to move the sampling position. The other factors which upset the uniformity of the particle distribution are sedimentation and inertial effects when the gas passes round bends or obstacles to the flow. These factors are discussed in the next section.
Andrew G. Clarke, George Bartle

4. Particulate emissions — optical and other methods for continuous monitoring from a point source

All particles emitted from a stack or vent give rise to various nuisances, depending upon the size, quantity and chemistry of the particles. Plume visibility and haze are a major nuisance resulting mainly from the emission of finer particles, whereas larger particles give rise to local ground level deposits.
Richard Horne

5. Gas sampling and conditioning

Most measurements on gaseous industrial emissions are carried out by extracting a sample from the flue or chimney and transporting it either to a continuous analyser or to an absorption system for later off-line measurement. This chapter will demonstrate that gas sampling, transport and conditioning are by no means trivial operations. They can lead to significant errors in the final measurement if not undertaken correctly and the hardware represents a major part of the costs of the overall analytical system.
Andrew G. Clarke

6. Batch sampling and wet chemical methods of gas analysis

Much of this book deals with sophisticated optical and electronic instruments for continuous monitoring of gaseous pollutants. These have increasingly replaced traditional methods involving batch sampling and wet chemical methods of analysis. However, there are some species where continuous analysers are not available. There are also applications where results are only required periodically and therefore the additional expense of a continuous monitor is not justified. There are many industrial sites with well-equipped chemical laboratories which are quite capable of undertaking analyses of gases or liquids arising from a sampling programme relating to a flue gas or process gas stream. So there will continue to be situations where off-line analysis makes practical and economic good sense. More than this, batch sampling and subsequent analysis has been — and will continue to be — the basis of many reference test methods and for this reason, if for no other, they will continue to be used.
Andrew G. Clarke

7. Optical methods of analysis. 1 Infra-red

This chapter will concentrate on measuring devices utilizing the principle of the absorption of infra-red radiation by gaseous species and their subsequent use in industrial air pollution monitoring. This method — particularly the use of non-dispersive infra-red (NDIR) measurements — provides the most robust technique for the continuous monitoring of polluting gases, combining accuracy of result, together with long life of analysers and relatively low maintenance costs.
Colin Blackmore

8. Optical methods of gas analysis. 2 Visible and ultra-violet

Gas analysis by optical methods is a wide-ranging subject with numerous techniques available for the analyst. Choosing a particular method can be a confusing and difficult choice for the inexperienced. The following rules can be applied when investigating the suitability of any given method.
John Turnbull

9. Volatile organics

Organic compounds contribute to a range of atmospheric pollution problems. The issue that has required the general control of organic compounds is photochemical smog (Seinfeld et al., 1991). Organic compounds also contribute to climate change through global warming and depletion of stratospheric ozone. In addition, some organic compounds are toxic and many are odorous.
Stephen Richardson, Nigel Gibson

10. Sampling and analysis of PAH, dioxins and furans

Of the organic micropollutants emitted from combustion systems, the chemical groups comprising, dioxins and furans, and polycyclic aromatic hydrocarbons (PAH) are of most concern because of their associated health hazard. The concern over dioxins and furans arises from a number of animal studies which show that for some species they are extremely toxic at very low levels of exposure. The extrapolation of these animal data to humans, though contentious, has led to dioxins and furans acquiring their notoriety as one of the most toxic group of chemicals known to humans. PAH are also seen as highly toxic since, among the environmental chemical groups, they comprise the largest group of carcinogens. PAH adsorbed on airborne particulates are believed to be major contributors to the higher death rate from lung cancer in urban areas as compared with rural areas.
Paul T. Williams

11. Electrochemical and other non-optical techniques

Electrochemical devices have found very wide application in the field of toxic gas monitoring in the context of industrial hygiene. Until about 10 years ago they had not been as widely used for stack gas or exhaust monitoring with the exception of the zirconia sensor for oxygen. However, there are now many portable flue gas analysers based on these cells offering the potential to measure up to about six gases in one unit. There are no problems with sensitivity to the pollutant gases found in flue gases since the concentrations are generally higher than in ambient factory atmospheres. However, there may be more severe problems of selectivity, resistance to contamination and operational life than would be encountered in industrial hygiene applications.
Andrew G. Clarke, Ian Watson

12. Calibration of continuous gaseous emission measuring systems

The calibration of continuous emission measuring systems (CEMS) is primarily concerned with determining the accuracy of the measuring system under investigation. Some operators of CEMS consider calibration to comprise simple zero and span checks plus adjustment, which involves setting the zero and span responses of the CEMS to the known values of standard reference gas mixtures (SRGM). Adjustment often follows from a zero and span check and the deviation or degree of adjustment required is sometimes used as a measure of accuracy. However, such rudimentary procedures cannot stand alone and qualify as valid calibration because the accuracy assessment is insufficient.
David S. Walker

13. Calibration gases

Calibration gases are fundamental to the validity of industrial air pollution monitoring. Since most monitoring equipment used in this field is comparative, it is necessary to use a calibration gas to calibrate any analysers or sensors on a regular basis. Hence, it is necessary to select the most appropriate calibration gas standard for these determinations bearing in mind any further requirements of accuracy, traceability and stability that may be required by the pollution control authorities.
John Scawin

14. Data logging

Recording data from instrumentation is an important part of any monitoring system. With a growing environmental conscience, industrial plants can be fined or shut down for producing high emissions. Thus, emission monitoring systems have become critical. This chapter examines the different methods used to evaluate processes against legislation. Chart recorders, data loggers and Personal Computer-based systems are discussed.
Richard Grant

15. Quality assurance and quality control in emissions monitoring

Emission monitoring is a relatively complex task. It will normally require a number of different items of equipment, and measurement of more than one parameter, and many of the techniques require collection of samples with subsequent transportation and laboratory analysis. An effective emission monitoring programme will produce reliable and accurate results, but there are many factors which can affect the validity of these results. Identifying these factors and effectively controlling the emission monitoring programme to produce reliable, valid results can be a complex task.
Simon Medhurst, David Miles

16. Statistics in relation to emissions monitoring

Specified emissions limits can provide a bewildering range of criteria:
  • ‘The emissions shall not exceed x mg/m3
  • ‘No more than 5% of the 48-hour averages should exceed y mg/m3 in a calendar year’
  • ‘The calendar monthly average should not exceed z mg/m3
  • ‘95% of hourly averages for each rolling 24 hours should not exceed the limit value and the peak hourly value shall not exceed 1.5 times the limit value’
  • ‘15-minute mean emissions shall not exceed x mg/m3 for more than 5% of the 15-minute periods of the process operation in any day and no 15-minute period shall exceed y mg/m3
Andrew G. Clarke


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