Document 7R3e2gqx8pY5zoLK3LE7Rqb3a

864 CHAPTER. 47 .' 1946 Guide Heating Load First Hour .Water-- ............. .......... Evaporation.TM__ ________ Heated to 212 F 212 F 212 F 66.7% 66.7% 140 X 120,120 || X 7,920 0.667 X 116,520 0.667 X 9,800 Bto = 51,688 - 3,408 17,040 = 77,680 = 6,530 Total Per Ton.............................. ______ ________;................. ...................... ;...__ 156,346 For 6 ton__ 1TM............. ...... Steel plates...... .................... 390 F Radiationb........,, ____ 422 F Avg 6 X 156,346 ' 320 X 30,000 X 0:i2 352 X 856 X 0.30 = 938,076 = 1,152,000 = 90.394 Total....... _............. ............. .. ....... ................................. ....... ............... ______ 2,180,470 Heating Load Second Hour Sand_______ ____ _________ 400 F Binder............. ...... .... ....... 400 F al*120'120 II X 7,920 = 68,432 4,512 Evaporation__________ ___ 33.3% 33.3% 0.333 X 116,520 0:333 X . 9,800 =_: 38,840 3.270 Total Per Ton. .. _______ 115,054 For 6 ton________________ Steel plates........................... 460 Radiationb........................... 575 6 X 115,054 = 690,324 70 X 30,000 X 0.12 = 252,000 505 X 856 X 0.30 = . 129,684 1 079 ona Binder oxidizes and liberates heat, which is neglected in this calculation. bAverage value of coefficient is less than 0.3 because oven is not tip to 575 F.'' This is neglected. 422 F is arrived at by taking area under curve as compared to area under 575 F ordinate. ESTIMATING METHODS Values based on practical experience are available for rough estimating of drying problems. The temperature will drop approximately 8.5 F per (grain of water evaporated) (cubic foot of air, measured at 70 F) or approximately 0.62 F per pound of air at any temperature. Air will drop 55 F per cubic foot for each Btu extracted. Generally air will absorb from 2 grains to 5 grains per cubic foot of air in one passage through an air dryer, depending on the temperature and the degree of contact with the material. The amount of steam required to evaporate a pound of water will vary from 1.5 lb to a more usual figure of from 2.5 to 3 lb of steam per pound of water evaporated. . BIBLIOGRAPHY Drying Apparatus, by H. C. Russell (A.S.H.V.E. Transactions, Vol. 18,1912, p. 76). Commercial Drying Apparatus, by L. P. Dwyer (A.S.H.V.E. Transactions.-VoI. 22, 1916, p..479). Drying Systems 865 Artificial Drying with Special Reference to.the Use of Gas, by G. C. Shadwell (A.S.H. V.E. Transactions, Vol. 23, 1917, p. 231). Drying by Evaporation, by F. R. Still (A.S.H.V.E. Transactions, Vol. 23; 1917, p. 255). High Temperature Drying, by Burt S. Harrison (A.S.H.V.E. Transactions, Vol. 24, 1918, p. 7). . The Temperature of Evaporation, by W. H. Carrier (A.S.H.V.E. Transactions, Vol. 24, 1918, p. 25). Address on Dehydration, by H. C. Gore (A.S.H.V.E. Transactions, Vol. 24, 1918, p. 323). Food Dryers and the Use of School Houses for Drying,' by W. Li Fleisher (A.S.HiV.E. Transactions, Vol. 24, 1918, p. 339). Memorandum Concerning Fruit and Vegetable Dryers, by Alfred S. Kellogg. (A.S.H. V.E. Transactions, Vol. 24, 1918, p. 359). . , Progress in the Dehydration Industry, by C. E. Mangels'(A.S.H.V.E. Transactions, Vol. 26, 1920, p. 99). Dehydration, by Ralph H. McKee (A.S.H.V.E. Transactions, Voi. 26, 1920, p. 105). Commercial Dehydration, by J. E. Whitley (A.S.H.V.E. Transactions, Vol. 26, 1920, p. 551). Drying of Fruits and Vegetables, by Ray Powers (A.S.H.V.E. Transactions, Vol. 27, 1921, p. 241). Drying as an Air Conditioning Problem, by A. W. Lissauer (A.S.H.V.E. Trans actions, Vol. 27, 1921, p. 251). A Chronological Survey of Drying and Driers, by J. E. Bolling (A.S.H.V.E. Journal, Vol. 27, October, 1921, p. 715). Dehydration and Freshening of Codfish, by Henry W. Banks, 3D (A.S.H.V.E. Transactions, Vol. 28, 1922, p. 143). Construction of Farm Dehydrators in California, by A. W. Christie and G. B. Ridley (A.S.H.V.E. Journal, Vol. 29, 1923, p. 687). Study of Air Velocity and Temperature in Vegetable Dehydration, by A. W. Christie and K. Matsumoto (A.S.H.V.E. Journal, Vol. 33, June, 1927, p. 381). Air Conditioning and Food Dehydration (Heating and Ventilating, December, 1942, p. 35). Adiabatic Drying of Hygroscopic Solids, by A. M. McCready and W. L. McCale (Transactions, American Institute Chemical Engineers, 1933). Limitations of Diffusion Equations in Drying, by O. A. Hougen, H. J. McCauley and W. R. Marshall (Transactions, American Institute of Chemical Engineers, 1940). Factors Influencing the Performance of Rotary Dryers, by C. F. Prutton and C. O. Miller (Transactions, American Institute of Chemical Engineers, Part 1, February, 1942; Part 2, August, 1942). , Drying of Solids by Through Circulation, by W. R. Marshall and O. A. Hougen (Transactions, American Institute of Chemical Engineers, 1942). Factors that Influence Drier Performance, by A. Weisselberg (Chemical and Metallur gical Engineering, August, 1932). Typical Dryer Calculations, by O. A. Hougen (Chemical and Metallurgical Engi-. ncering, January and March, 1940). Symposium on Drying, Articles by W..K. Lewis, W. H. Carrier, A. E. Stacey, Jr. and R. S. Fleming,. R. G. Metz, G. B. Ridley, C. O. Lavett, D. J. Van Marie (Journal Industrial Engineering Chemistry, May, 1921). Principles of Drying Lumber and Humidity Diagram, by H. D. Tiemann (Forest Service Bulletin 104, 1912).