COST OF PLANT. The estimated cost of the two crude batteries with their condensers and interconnecting piping and pumps, based on costs at the time of construction, is shown in Table 3 following. TABLE 3.-Detailed costs of two crude batteries at Avon refinery. a Only that proportion chargeable to the conventional crude still plant is carried to the total column. RERUNNING PLANT. The estimated cost of the rerunning plant is given in the description of the topping plant. An amount proportional to the distillate handled from these crude stills should be charged to them. The total estimated cost of the crude batteries and the necessary rerunning apparatus is therefore $224,945, or approximately $16.80 per barrel of normal daily capacity. This figure is considerably higher than the cost of the toppers of similar duty, mentioned later. DATA FROM EXPERIMENTS. During the writer's inspection of the plant various experiments were made to determine the efficiency of the different apparatus. Owing to the lack of facilities, these experiments were necessarily incomplete, but the details obtained and the computed results are listed in the following pages. An ultimate analysis of the fuel oil used at the plant follows: The theoretical fuel consumption for removing a 25 per cent cut from 1 pound of oil as fractionated below would be as follows, if no heat is lost in the batteries and the heat recovered in the exchangers is considered: Where the mean specific heat of the oil=0.45, approximately, latent heat of distillate=125 B. t. u., or 31.5 calories, approximately, specific heat of the vapors=0.50 B. t. u., approximately, oil leaves the exchangers at 250° F. (121.1° C.), approximately, the heat required is as follows: Heat 0.938 pound of oil 250 B. t. u. 300° F. (121.1-148.8° C.).... 0.938 (250-300° F. 121.1-143.8° C.) × 0.45 =21. 12 Evaporate 0.058 vapors.... pound Heat 0.879 pound of oil 300350° F..... Evaporate 0.0346 pound of vapors... Heat 0.845 pound of oil 350- Heat 0.820 pound of oil 400- or Heat consumed per pound of oil topped at 100 per cent efficiency=96.70 B. t. u., 24.40 calories. TABLE 4.-Furnace and stack temperatures, with heat losses and furnace efficiencies, con TABLE 4.-Furnace and stack temperatures, with heat losses and furnace efficiencies, conventional crude stills-Continued. One barrel of 26° B. (specific gravity, 0.8974) oil weighs 314.4 pounds; therefore the total heat required to top 1 barrel of this oil at 100 per cent efficiency would be 96.70 x 314.4-30,402.48 B. t. u., or 7,670 calories. However, Table 6 (p. 28) shows that in 1916 these stills actually зed an average of 0.011 barrel of fuel to 1 barrel of oil topped, which with 18° B. oil is 68,325 B. t. u., or 17,217.9 calories. In addition some steam was used for agitation, which can be approximated as 320 boiler horsepower, or 0.575 boiler horsepower to a barrel of crude run which contains 19,250 British thermal units, making a total of 87,575 British thermal units consumed." The over-all efficiency of the crude batteries is therefore or 34.8 per cent. HEAT EXCHANGERS. 30,402 87,575' Average daily temperature readings for November, 1916, on the fluids passing the heat exchangers are given in Table 5, with the computed rates of heat transmission in the apparatus. TABLE 5.-Average residuum and crude-oil temperatures in the heat exchangers of conventional crude stills during November, 1916. a The figures for steam consumption were furnished by Mr. C. Stamm, superintendent of the refinery. TABLE 5.-Average residuum and crude-oil temperatures in the heat exchangers of conventional crude stills during November, 1916—Continued. Where K FS (T-t) -British thermal units transferred from residuum to crude oil per square foot per hour per degree of mean temperature difference. K= FS (T-t) Hom =British thermal units apparently transferred from residuum to crude oil per square foot per hour per degree of mean temperature difference. F=weight of fluid passing per hour. S=specific heat of fluid (0.4 for residuum, 0.45 for crude). H-heating surface of the exchanger computed as a mean between external and internal surfaces. a=difference between temperatures of fluids at beginning. 0 difference between temperatures of fluids at end. It will be noted that the flue-gas analyses show the results of normal operation of the crude stills using 165 to 191 per cent excess air for combustion, which corresponds to a fuel loss of 18 to 20 per cent. By lowering the dampers this loss could be reduceed to 10 per cent, and, undoubtedly, could be reduced still further. Attention is called to the stack-draft data recorded in Table 4 (p. 12). The draft was greatly in excess of what should normally be required in the operation of the plant. Designers of oil-burning apparatus have been greatly influenced by the present designs of coal-burning equipment, and little dependable information has been compiled regarding correct design for oil-burning equipment. Results show conclusively, however, that oil fuel requires a relatively slight draft for proper combustion, and that the quantity of excess air can be reduced considerably. The setting for crude stills does not readily adapt itself to an arrangement permitting any considerable reduction of stack-gas temperatures. However, topping plants can be so constructed as to reduce these temperatures decidedly. In fact, the stack-gas temperatures may be made to approach the temperature of the entering oil by making the gases flow counter to the oil. In the topper designed by Bell, stack temperatures of 385° F. have been attained |