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NOx control technologies for coal combustion
Book Review
NO, Control Technologies
for Coal Combustion
Anna - Karin Hjalmarsson IEA Coal Research, Gemini House, London SW15 6AA. UK, 1990, ISBN 929029 177X, pp. 102, &60/&l 80 (member/non-member countries).
About the middle of this century concern about the environment got so far as to produce regulations aimed at pollution control judged mainly by air quality standards. While such measures were a step forward they were soon considered insufficient in that stricter enforcible emission controls at source were necessary. Japan, USA and FRG were leaders in formulating national standards and pioneered methods of complying. In recent years IEA Coal Research has s ies of provided an invaluable ment. publications on coal and the enviro \ In particular since 1987 eleven reports dealing with acid emissions from coal-fired plants, flue-gas control systems, emission standards, climatic effects, trace elements and waste management have been published. This latest report in the series is concerned with NO,, claiming to describe the state of the art NO, emission control technology. This claim is well justified by the clarity, comprehensive coverage and concise treatment which makes this at one and the same time a valuable reference work for the specialist, for all who are anxious to be informed of the issues in order to support national environmental protection and for students in many disciplines. The control of nitrogen oxides (NO,) is defined as the control of nitric oxide (NO) and nitrogen dioxide (NO,), but attention is drawn to nitrous oxide (N,O) which is formed in small quantities and has begun to be measured during recent years because it can cause depletion of stratospheric ozone and is one of the
greenhouse gases. Recent work has cast doubt on earlier measurements that may be too high because N,O is formed through interaction of NO,, SO2 and H,O in sample containers. Chapters on regulations on NO, emissions, control of NO, emissions through combustion measures, catalytic and reduction, combined SOJNO, processes illustrate how legislative and regulatory requirements determine the degree and method of treatment required. This survey of current technology includes some account of operational experiences; extremely useful information on the costs of NO, control is given in a later chapter enhancing the usefulness of the information especially in comparing and evaluating the various control techniques. Advanced combustion technologies can be doubly beneficial in procuring lower emissions and higher efftciencies. Those described include atmospheric and pressurized fluidized bed combustion, integrated combined cycle power generation, gasification and slagging combustors. Apart from atmospheric fluidized bed combustion, of which some 30 installations of up to 110 MW output are listed with their performance achievements, examples of most of the other advanced technologies are few and with only short term or no experience on large scale utility installations but they do hold out the best prospects for future coal-based electricity generation. A chapter providing an overview of activities to reduce NO, from coal-fired plants in 12 IEA countries which have or
plan to introduce measures for control shows commendable commitment but also reminds us without saying as much that there are many other industrial nations that are doing nothing about it. Complimentary information on national standards of NO, emission that have been adoptedare given in an appendix. One of the great difficulties in attempting to assess or compare national emission standards and their effectiveness is that different limits are used to express concentration and emission of NO,. Another useful appendix provides guidance on analysis of NO, conversion equations and a simple conversion chart for NO, emissions from coal. There are eleven pages of references mostly from the past three years. The author has been at great pains to assist the reader by giving full particulars of sources, and in many cases by providing translations of titles or other relevant details. A summary and conclusions are very well drawn to round off a most satisfactory monograph. Prophetically it is stated ‘in the future total optimisation of the whole power plant will become essential, taking plant efficiency as well as emission control into account. This will lead to the integration of combustion and emission controls’. It might as well be added that environmental control is a global problem requiring international solutions. J. Gibson
FUEL, 1990, Vol 69, November
1461
NO, Control Technologies
for Coal Combustion
Anna - Karin Hjalmarsson IEA Coal Research, Gemini House, London SW15 6AA. UK, 1990, ISBN 929029 177X, pp. 102, &60/&l 80 (member/non-member countries).
About the middle of this century concern about the environment got so far as to produce regulations aimed at pollution control judged mainly by air quality standards. While such measures were a step forward they were soon considered insufficient in that stricter enforcible emission controls at source were necessary. Japan, USA and FRG were leaders in formulating national standards and pioneered methods of complying. In recent years IEA Coal Research has s ies of provided an invaluable ment. publications on coal and the enviro \ In particular since 1987 eleven reports dealing with acid emissions from coal-fired plants, flue-gas control systems, emission standards, climatic effects, trace elements and waste management have been published. This latest report in the series is concerned with NO,, claiming to describe the state of the art NO, emission control technology. This claim is well justified by the clarity, comprehensive coverage and concise treatment which makes this at one and the same time a valuable reference work for the specialist, for all who are anxious to be informed of the issues in order to support national environmental protection and for students in many disciplines. The control of nitrogen oxides (NO,) is defined as the control of nitric oxide (NO) and nitrogen dioxide (NO,), but attention is drawn to nitrous oxide (N,O) which is formed in small quantities and has begun to be measured during recent years because it can cause depletion of stratospheric ozone and is one of the
greenhouse gases. Recent work has cast doubt on earlier measurements that may be too high because N,O is formed through interaction of NO,, SO2 and H,O in sample containers. Chapters on regulations on NO, emissions, control of NO, emissions through combustion measures, catalytic and reduction, combined SOJNO, processes illustrate how legislative and regulatory requirements determine the degree and method of treatment required. This survey of current technology includes some account of operational experiences; extremely useful information on the costs of NO, control is given in a later chapter enhancing the usefulness of the information especially in comparing and evaluating the various control techniques. Advanced combustion technologies can be doubly beneficial in procuring lower emissions and higher efftciencies. Those described include atmospheric and pressurized fluidized bed combustion, integrated combined cycle power generation, gasification and slagging combustors. Apart from atmospheric fluidized bed combustion, of which some 30 installations of up to 110 MW output are listed with their performance achievements, examples of most of the other advanced technologies are few and with only short term or no experience on large scale utility installations but they do hold out the best prospects for future coal-based electricity generation. A chapter providing an overview of activities to reduce NO, from coal-fired plants in 12 IEA countries which have or
plan to introduce measures for control shows commendable commitment but also reminds us without saying as much that there are many other industrial nations that are doing nothing about it. Complimentary information on national standards of NO, emission that have been adoptedare given in an appendix. One of the great difficulties in attempting to assess or compare national emission standards and their effectiveness is that different limits are used to express concentration and emission of NO,. Another useful appendix provides guidance on analysis of NO, conversion equations and a simple conversion chart for NO, emissions from coal. There are eleven pages of references mostly from the past three years. The author has been at great pains to assist the reader by giving full particulars of sources, and in many cases by providing translations of titles or other relevant details. A summary and conclusions are very well drawn to round off a most satisfactory monograph. Prophetically it is stated ‘in the future total optimisation of the whole power plant will become essential, taking plant efficiency as well as emission control into account. This will lead to the integration of combustion and emission controls’. It might as well be added that environmental control is a global problem requiring international solutions. J. Gibson
FUEL, 1990, Vol 69, November
1461