H. Brauer ·YB.G.Varma Air Pollution Control Equipment With 285 Figures and 53 Tables Springer-Verlag Berlin Heidelberg New York 1981 Professor Dr.-Ing. Heinz Brauer Technische Universitat Berlin, Germany Professor Dr. Yalamanchili B.G. Varma Indian Institute of Technology Madras, India ISBN -13: 978-3-642-67907-0 e-ISBN -13: 978-3-642-67905-6 DOl: 10.1007/978-3-642-67905-6 Library of Congress Catalogmg m PublIkatlOn Data: Brauer, Hemz, 1923-Air PollutIOn control equip ment. BiblIography: p. Includes index. I. Air-PurIficatIOn-Equipment and supplies. 2. PollutIOn control equipment. I. Varma, Yalamanchili B G" 1936-joint author. II. Title TD889.B72 681'.76 80-39760 ISBN -13: 978-3-642-67907-0 ThiS work IS subject to cOPYrIght All rIghts are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of IllustratIons, broadcastmg. reproduc lion by photocopymg machme or Similar means, and storage m data banks. Under §54 of the Gennan Copyright Law where copies are made for other than private use a fee IS payable to "Verwertungsgesellschaft Wort", Munich. © SprInger-Verlag Berlin, Heidelberg 1981 Softcover reprint of the hardcover 1st editIon 1981 The use of registered names, trademarks, etc. m this publIcation does not Imply, even In the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. 2152/3020-543 10 Preface This book has arisen directly from a course on Air and Water Pollution Control delivered by the first named author at the Technical University of Berlin. Extractions of this course have been presented in Brazil, Turkey and India. It was at the Indian Institute of Technology of Madras where the first named author got in contact with Professor Varma, who turned out to be a suggestive, cooperative coauthor. This book is addressed primarily to chemical, environmental and mechanical engineers, engaged in the design and operation of equipment for air pollution control. But it will certainly be helpful to chemists and physicists confronted with the solution of environmental problems. Furthermore it is intended as a text book for engineering courses on environmental protection. The goal of the book is the presentation of knowledge on design and operation of equipment applicable to the abatement of harmful emissions into air. The technology of air pollution control is of relatively young age, but it has already achieved a high degree of performance, due to the research and develop ment work invested in the last decades in this field. The first two chapters deal with environmental protection engi neering. A short review of the development of environmental consciousness and of legal actions taken in the last two centuries in Germany is presented. A preliminary last step was made in 1974. Environmental technology has been developed particularly in the last 50 years. The appropriate technology was therefore largely available, when legislation imposed severe restrictions on harmful emissions. Chapter 3 gives a short survey of air pollution techniques. In Chapters 4 to 7 design and operation of the most important types of dust removal equipment are discussed, namely cyclones, wet dust scrubbers, fibrous filters, and electrical precipitators. A special chapter is then devoted to mist separation, that is not only related to wet dust scrubbing but also to absorption of gaseous pollutants, when the liquid absorbent is dispersed in the gas mixture. In the following Chapters 9 to 12 physical, biological, and chemical processes and the related equipment for the removal of gaseous pollutants are discussed. The technical equipment includes absorbers and adsorbers as well as biological and chemical reactors. VI Preface I should like to thank many people, especially my coauthor for his engagement in this work. I am also most grateful to all of my coworkers, the scientific, technical, and administrative personnel of the Institute of Chemical Engineering of the Techni cal University of Berlin. Special mention deserve Dr.-Ing. R. Spilger, who relieved me of much of the daily routine work, Mrs. Strauss, who typed and retyped the manuscript with never relaxing carefulness, and Mrs. Westphal, who accepted the re sponsibility for the preparation of a few hundred figures. Finally, I should like to thank my wife for her never ending patience and love. It is to her that this book is devoted. To B.B. Berlin, December 1980 Heinz Brauer Contents Chapter 1 Introduction to the Problems of Environmental Protection . . . . . . . . . . . . . . . . Chapter 2 Integration of Technical Measures Taken for Environmental Protection . . . . . . . . . 29 Chapter 3 Survey on Technical Processes and Equipment for Air Pollution Control and Some Fundamentals . . . . . . . . . 43 Chapter 4 Design and Operation of Cyclones 67 ChapterS Design and Operation of Wet Dust Scrubbers. 107 Chapter 6 Design and Operation of Fabric Filters 149 Chapter 7 Design and Operation of Electrical Precipitators . . . . . . . . . . 183 Chapter 8 Design and Operation of Mist Separators 219 Chapter 9 Design and Operation of Absorption Equipment. . . . . . . . . . . . . . . . 241 Chapter 10 Design and Operation of Adsorption Equipment ........... . . .. 307 Chapter 11 Design and Operation of Equipment for Biological Waste Gas Treatment . . . . . . 335 Chapter 12 Design and Operation of Equipment for Chemical Waste Gas Treatment. 347 Subject Index . . . . . . . . . . . . . . 383 Chapter 1 Introduction to the Problems of Environmental Protection Contents 1. Environment-Environmental Protection - Environmental Engineering 2. Sources of Pollutant Emission 3 3. Environmental Pollution 9 3.1 Air Pollution . 9 3.2 Water Pollution . . . . 16 3.3 Soil Pollution . . . . . 19 4. Actions Taken Against Environment Pollution and Results Achieved 20 4.1 Laws, Regulations, and Standards for Environmental Protection . 20 4.2 Air Pollution Abatement . 21 4.2.1 Dust Emission Abatement 21 4.2.2 Gas Emission Abatement . 24 4.3 Water Pollution Abatement 24 4.4 Soil Pollution Abatement 26 5. References 27 1. Environment-Environmental Protection Environmental Engineering Through centuries and milleniums. never ending hardships and deeply rooted anxieties as well as hopes for a better future have impressed their signum on man, thereby determining man's behavior, his outlook on life and his environ ment. Hunger, diseases, inclemency of weather, and destructive natural forces have at all times been man's companions. In order to survive, and in order to shape a better future, with more freedom from want and fear man saw only one possibility of reaction to those formidable challenges: to shape his environment according to his wishes. He engaged himself in a seemingly endless struggle with nature, with his natural environment. Through centuries and milleniums, man experienced the glory of victory. However small the success was, it encouraged him to carryon his fight. But slowly it also dawned upon him that victory is not only glory, but that victory also encompasses destruction. Finally, man began to realize that the destructive forces he commanded began to shape and misshape his environment to such an extent that his own life and his own future were endangered. Something 2 Chapter 1: Introduction to the Problems of Environmental Protection has gone wrong with this Promethean struggle. Man must learn to control his creative power that can be applied to constructive and destructive deeds as well. In the language of modern science, man has in certain parts of his environment disturbed or even destroyed an ecological equilibrium of nature. If this continues as in the past, man will destroy natural ecology and thereby the basis of his own life and future. To restore where necessary and to protect the ecological equilibrium in all of his environment, environmental protection has gained priority on the list of works of man. Science is the offspring of doubts. Man therefore asks what is ecological equilibrium. Is there an ecological equilibrium for the whole earth or only for restricted parts of it? Is this ecological equilibrium a static system or is it, as man tends to assume, a dynamic system? What is the role of natural evolution in ecology and what are the forces behind it? How does man command forces that effect evolution? Can man attach values like good and bad to observed results of evolution within our ecological system? How do we value the disappearance of the dinosaurs at the end of the mesozoic era, about 60 million years ago? Or how do we value the successful fight in many countries of the world, against the mosquito anopheles, the carrier of the malaria parasite that caused the death of millions of people even in our times? There are far more questions about ecology and its natural equilibrium. There are no easy answers. As a matter of fact, it seems that we are at present not in a position to say clearly and without doubt when to lament changes in our natural environment caused by man's activities. We are not sure any more whether philosophy and religion furnish us with ethical and practicable standards by which we can measure and value the effect of our activities on our environment. Without ethical standards man will be helpless and will be lost in a world he started off to conquer and to shape according to his will. There are many arguments in favour of a restricted outlook on environment and all its problems. Accepting man as the most prominent and certainly dom inating figure of the environment, it may be accepted, that man himself sets the rules for judgement of his own affairs. It localizes environmental problems. Environment is the space of man's activities. With respect to each individual, environment may be interpreted as the world in which our fellow-men live. It is this world, it is our fellow-men that need protection. Environmental protec tion defined in this way includes ethical aspects. Environmental protection is a basic necessity for man, N aturam protegere necesse est. Man made his strongest impact on his natural environment after he had devel oped technology, which he used for the creation of a man-made and man-centered technical environment. Technical environment thus stands against natural envi ronment; but this is not necessarily the case. Technical and natural environment must be coordinated to the best of man himself. Man must apply technology not only to the creation of his technical environment but also to the protection of the natural environment. Application of technology to the protection of the environment leads to a new engineering discipline: Environmental protection 2. Sources of Pollutant Emission 3 engineering. The environment consists of three important spatial elements. which are air, water, and soil. Environmental protection engineering has to protect air, water, and soil against any serious disturbance of its own natural equilibrium. Technology supplies the tools but it is man who has to apply these tools for the benefit of his environment and his future. The immensity of the engineering problems involved in environmental protec tion can be deduced from the book by Meadows: "Limits to Growth" [1]. These problems remain widely unaffected by the models applied to the descrip tion of cultural, economic, and technological development of the world or parts of it. A team of scientists and engineers from the Netherlands has analyzed and described in detail the environmental problems that have to be solved [2]. Just to get an impression of the monetary consequences of environmental protection the United States of America may be taken as on example. The data are taken from the Journal" United States News and World" in 1970. In this year, President Nixon announced the "Pollution Central Program". For the following five years, it was estimated that environmental protection in the USA required 70 billion US dollars. Of this amount 72% were estimated to be necessary for the introduction and improvement of communal waste water treatment, 14% were estimated to be spent by industry in all fields of environmental protection, and 8,5% for the abatement of emissions from motor cars. The percentages given are probably the same for all industrialized countries. Waste water treatment will in all cases require the bulk of the expenditure. Air pollution control requires only a relatively small part of the overall expendi ture. The problems of environmental protection can only be solved by the coordi nated endeavours of various engineering and scientific disciplines: physics. chemis try, medicine, biology, chemical engineering, and social sciences. For any single discipline it is impossible to solve the problems. Many scientific and engineering disciplines will have to contribute to the solution of the problems. The engineers' contribution will be primarily the development, design, and operation of equip ment for the abatement of harmful emissions. It is to this branch of pollution control to which the main part of this book is devoted. In the following sections it will become clear that environmental pollution is still primarily a local problem. It must be observed therefore that solutions to environmental pollution control cannot be generally applied to the problems in places with different conditions. Local conditions have to be carefully analyzed in search of an optimum solution to the given problem. 2. Sources of Pollutant Emission Pollutants are emitted from sources defined by their 1. size. 4 Chapter I: Introduction to the Problems of Environmental Protection 2. strength, 3. species of pollutant. With a certain simplification, the sources of pollutant emission may be divided into two groups: 1. independent single sources, 2. field of sources. The first group of emission sources is easily understood. The second group, however, needs explanation. A field of sources is what is sometimes called diffuse sources. When a large number of sources of generally little strength are combined with a unit distinctly separated from the surrounding space, this type of emission unit is called a field of sources. As far as spreading and distribution of the pollutants in the environment is concerned, the whole unit and not the individual elements have to be considered as a source of emission. Sources of emission contained in a field cannot be considered separately. These sources are very close together and the emissions will be mixed together even while they are still within the spacial dimensions of the source field. Both types of sources, single sources and fields of sources, will be considered in detail. There are three groups of independent single sources: 1. point sources, 2. line sources, 3. area sources. The best known point sources are high chimneys. Independent of a visible or invisible plume emerging from the stack, people are convinced that stacks are sources of very strong emissions. Dividing the emission flow rate by the emission area, i. e. the exit area of the stack, the emission flux is obtained. Because of the small exit area, the emission flux of a stack will always be very large. The emission properties of high stacks demonstrate the emission properties of independent point sources: 1. defined locality of emission, 3. great height of emission [m], 3. type of emission, 4. great strength of emission flow rate [kg/s], 5. great strength of emission flux [kg/sm 2]. The height of emission must be seen in relation to houses and technical installa tions in the surroundings of the point source. Independent line sources are, for example, waste water conduits, while waste water treatment tanks, harbours, and estuaries may serve as examples for area sources. Fig. 1 presents a view on the largest waste water treatment plant in Germany [3J. The height difference between independent line and area sources and the environment is in most cases of no importance. Because of the relatively large area of these two sources, the emission flux may be relatively small, the emission flow rate and the nuisance to the population living in the surround-