Document 9Ly7p95294k11KLEjRL9bQxke

864 CHAPTER 33 1958 Guide temperature conditions. Silica gel and alumina exhibit a strong preference for water vapor whereas charcoal does not. Combustion Devices This group of industrial air cleaners entails the use of high temperatures or catalysis combined with some elevation in temperature to destroy or de compose organic and some inorganic gases which create obnoxious odors. The devices are divided into those in which combustion is obtained by use of liquid or gaseous fuels and the secondary air for combustion is provided by the contaminated air. In essence, the simplest form involves passing the contaminated air through the combustion chamber of a boiler or fire box. Special fire boxes or brick checkerwork may also be employed. Catalytic devices consist of noble metal packed into frames in the form of ribbons or screens or may be ceramic granules coated with noble metal catalysts. The frames or packing are placed in a housing over which the gas stream to be decontaminated is passed. The contaminants break down and are reduced to elemental gases of an innocuous nature. Catalysts reduce the amount of heat necessary but may become contaminated by sulfur or other elements. - The performance of a combustion device is dependent upon the reten tion period of the contaminant in the high temperature zone. Removal or destruction is thus dependent on velocity and surface area of the heat transfer device. If properly designed, obnoxious odors are removed. The resistance of the direct combustion unit is negligible since it is an integral part of the fuel combustion system. Catalytic devices behave in a manner comparable to packed beds or filters except that they are not plugged by organic particulates but may be affected by inorganic solids. Maintenance of these types of units is essentially dependent upon the contaminants encountered. The direct combustion system requires little care other than that required by ordinary fuel burning equipment. Cata lytic units become contaminated slowly and will require removal for re activation at certain intervals depending upon the application. Economic factors may limit the use of direct combustion methods unless there is a demand for the heat generated. They may best be applied to processes employing combustion. Catalytic units require temperatures of at least 500 F and consequently it may be necessary to preheat the con taminated air to this value. REFERENCES 1 Bronchial Asthma and Allied Allergic Disorders, by S. S. Leopold and C.S- Leopold (Journal of the American Medical Association, March 7,1925, Vol. 84, p. `6 ' 734). .. * Air Cleaning as an Aid in the Treatment of Hay Fever and Bronchial Asthma, by Leo H. Criep, M.D., and M. A. Green, M.D. (Journal of Allergy, St. Louis, Jan ary, 1936, Vol. 7, No. 2, Page 120). The Bacterial Filtration Efficiency of an Electrostatic Air Cleaner, by 0. Lidwell (Journal of the Institution of Heating and Ventilating Engineers, 75 La Place, London, S.W.I., June 1951, Vol. 19, No.. 190, Page 139). * Dirt Patterns on Walls, by R. A. Nielsen (A.S.H.V.E. Transactions, Vo . > 1941, p. 247). Air Cleaning .865 * Industrial Dust, bv Philip Drinker and Theodore Hatch (McGraw-Hill Co.; New York, N. Y.). * Code For Testing Air Cleaning Devices Used in General Ventilation, Section I, Unit or Panel Type Air Filtering Devices, 1953 (Air Filter Institute). 7 A.S.H.V.E. Standard Code for Testing and Rating Air Cleaning Devices Used in General Ventilation Work (A.S.H.V.E. Transactions, Vol. 39,1933, p. 225). * A Test Method for Air Filters, by Richard S. Dill ("A.S.H.V.E. Transactions Vol. 44, 1938, p. 379). 3 Laboratory Design for Handling Radioactive Materials, Research Conference Report, Building Research Advisory Board, National Research Council, Washington D. C. 1952. BIBLIOGRAPHY Design and Application of Oil-Coated Air Filters, by H. C. Murphy (A.S.H.V.E. Transactions, Vol. 33, 1927, p. 73). Operation and Maintenance of Air Filters, by W. G. Frank (Heating, Piping and Air Conditioning, May, 1931, p. 378). Size and Characteristics of Air-Borne Impurities, by W. G. Frank.(Healing, Piping and Air Conditioning, January, 1932, p. 35). Fundamental Principles in the Design of Dry Air Filters, by Otto Wechsberg (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, April, 1933, p. 217). The Economic Factors in Converting Recirculated Air for Ventilation, by H. EZiel and Henry Sleik (A.S.H.V.E. Journal Section, Heating, Piping and Air Con ditioning, July, 1943, p. 367). ^ A.S.H.V.E. Research Report No. 1094--Air Filter Performance as Affected by Kind of Dust, Rate of Dust Feed, and Air Velocity Through Filter, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 44,1938, p. 415). A.S.H.V.E. Research Report No. 1122--Air Filter Performance as Affected by Low Rate of Dust Feed, Various Types of Carbon, and Dust Particle Size and Denp. 339h)y. F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 45, 1939, A.S.H.V.E. Research Report No. 1145--The Effect of Lint on Air Filter Performance by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 46, 1940, p. 60). A.S.H.V.E, Research Report No. 1169--Comparison of the Weight, Particle yount and Discoloration Methods of Testing Air Filters, by F. B. Rowley and R. C. Jordan (A.S H.V.E. Transactions, Vol. 47, 1941, p. 29). A'iF Research Report No. 1187--Economical Air Velocities for MechanVol 47r 194irap39ib)y F" B- Rowley and R- c- Jordan (A.S.H.V.E. Transactions, ^ ^.E. Research Report No. 1218--Overloading of Viscous Air Filters DurV*noli. A488, 1,n94?2i,edp.T4e3s7ts).> by F- B- Rowley and R- C. Jordan (A.S.H.V.E. Transactions, uaiy ^937^|fCi59^a*'C Rrec*PRa*'or> by G. W. Penney (Electrical Engineering, Jan- ClwtAStaUc Precipitation for Aircraft, by Howard E. Corbitt and Norman J. p . (Aero Digest, December, 1940, p. 132). IfflUIf'f8 J Selecting Equipment for Industrial Gas Cleaning, by C. E. Miller emical and Metallurgical Engineering, 45, March, 1938, p. 132-5). inn Precipitation, by W. A. Schmidt and E. Anderson (Electrical Engineer ing, 57, August, 1938, p. 332-338). 51, February ^1^2^^a935^)by A - W. Simon and L. C. Kron (Electrical Engineering, Mistm?H^Ctr tand Principles Involved in the Separation and Collection of Dust, Chemirni v"".e from Gases> by Evald Anderson (Transactions, American Institute of iemical Engineers, 16, 1924, Pt. 1, p. 69-86). actingtrjCal Precipitation of Solids from Smelter Gases, by Ross B. Rathbun (Trans- ' American Institute of Electrical Engineers, 41, 1922, p. 815).