Refinery Engineering Data on Distilling and Cracking of Petroleum. The total capacity of a horizontal still is approximately 0.14 d'1, d being the diameter and 1 the length of the still in feet. The heating area of a horizontal still is 1,0472 d 1 on the assumption that one-third of the shell is fired. In continuous stills a larger area may be fired on account of a higher minimum oil level. Continuous stills give a greater crude oil capacity than batch stills on account of the time required for charging and discharging batch stills. The amount of benzine or crude gasoline distilled is 1.5 d 1 barrel per day with continuous operation and with no other products distilled. The approximate amount of gasoline from crude oil stills per day per square foot of still bottom area not including charging time or time for bringing to distillation temperature is 1.0 barrel. This may vary according to the intensity of firing and the character of the crude. The approximate total fuel consumption in producing one gallon of 58° Be' gasoline in a still by cracking at 85 pounds pressure is 50,000 B.T.U. or 0.4 gallon of fuel oil. The total fuel consumption by cracking in tubes at 600 pounds pressure in producing one gallon of 58° Be' gasoline is 26,000 B.T.U. or 0.20 gallon of fuel oil. The report of the Western Petroleum Refiners' Association of September, 1919, on a pressure distillation process operating at 135 pounds per square inch pressure may be analyzed as follows: 0.164 gallons of 58° Be' gasoline was produced per square foot of heating area per hour after the oil was brought to the cracking temperature. 0.8 gallon of fuel oil equivalent to 112,000 B.T.U. was required to produce 1 gallon of 58° Be' gasoline. 200 cubic feet of gas was produced for each barrel of 58° Be' gasoline. 7.0 pounds of still carbon was produced per barrel of 58° Be' gasoline. A typical composition of the so-called carbon deposited in cracking stills is as follows. This sample was extracted with 70° Be' petroleum naphtha before testing: The following data represents the operation covering a long period of time of a very extensively used process for cracking oil, based on one still. % distillate of total charge per hour of distillation.. Gallons of 58.5° Be' gasoline per hour per sq. ft. of heat- Pounds of coal per gallon of gasoline (58.5° Be'). Equivalent gallons of fuel oil per gallon of 58.5° Be' gasoline 5,295 gallons .3,018 gallons 54 04% 57.0 % 30.8 % .143.1 gallons 1.46% 816 gallons 0.83% 270 sq. ft. 0 302 3.625 lbs. 0.25 CALCULATION OF HEAT EXCHANGES IN REFINERY CONDENSERS. In calculating amount of water required for condenser, use the following formula: w = W = 200 g gallons of water required per hour. incoming temperature of condensed water. te = Heat absorbed in condensing 1 gallon of gasoline to 60°F = 1,550 B.T.U. Heat absorbed in condensing 1 gallon of kerosene to 60° F = 2,400 B.T.U. Heat absorbed by oil in distilling off 50% from it as gasoline and kerosene is 2,100 B.T.U. per gallon of crude oil. Heat absorbed by oil in distilling to coke is approximately 3,000 B.T.U. per gallon. Amount of condenser surface required to properly condense one gallon of gasoline per hour 2 sq. ft.; 1 gallon of kerosene per hour = 1 sq. ft. This is lessened with cold water and with larger quantities of water and varies with the length and cross section of the condenser tubes. The cross section of the vapor line should be .05 sq. in. per gallon of gasoline per hour. The cross section of the condenser tubes may be reduced 1⁄2 after first of length and 4 more after second 1/3 of length. The same water used for condensing the benzine or gasoline fraction in crude distillation may be used to condense the kerosene fraction. |