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Popular Science Monthly 



AERIAL CONDENSER 



NAPHTHAS & FIXED GASES 



A - COr<DE NSE R TUBES 

 B- COLLECTOR PANS 

 C- COOLING COILS 

 0-COOLINS TANK 

 E- RUNNING TANKS 

 r - GAS TRAP 



#1 #1 ^t -tb^fii 



CYLINDER STOCR HEAVY LU6Hll«e LIGHT LUBtfTING GAS OIL 



RESIDUUM DISTILLATE DISTILLATE DISTILLATE 



ILLUMINATING OIL NAPHTHA 

 DISTILLATE DISTILLATE 



Fig. 1. First Separation of Crude Petroleum Into Groups by Distillation 



and other spi-cially distinguishing char- 

 acteristics. 



As cream, butter, cheese, casein, and 

 other products are derived from milk, so 

 are hundreds of different hydro-carbon 

 compounds lying between the extreme 

 limits of gasoline and cylinder stocks or 

 coke, separated from crude oil by frac- 

 tional distillation. These products are 

 divided into many different grades, 

 according to their physical and chemical 

 characteristics, and to the purpose for 

 which they are used and shipped to all 

 parts of the world, wherever an internal 

 combustion engine is run, a lamp burned, 

 or a wheel turned. 



Crude oils ma>- l)e divided into three 

 main families: lliose of paraffin, asphaltic 

 and cycIo-na|)hl!u>ne base. There is no 

 sharp line of separation fjetween these 

 groups, since most crude oils found in all 

 fields may contain mi.xtures in variable 

 percentages of hydro-carbons, belonging 

 to two or more fain il its. 



When the crude petroleum arrives 

 ilirough the pipe line and is deijosited 

 into storage tanks of large cajiacit)-, a 

 certain settling takes place. The semi- 

 solids which settle out consist of amor- 

 |)hous paraffin wax, mud or other earth>- 

 foreign matter antl impurities. 



First Stai^e — Separation into Groups 

 by Distillation 



From the storage tanks the crude oil 

 is pumped into a large cylindrical boiler, 

 called a "crude still." 



Distillation as applied to hydro-carbon 

 oil, is the separation of the more volatile 

 portions from the less volatile portions 

 by vaporization, and later condensing 

 them by passing the hot vapors through 

 a cooled tube. Light hydro-carbons like 

 gasoline, vaporize very readily, whereas 

 heavy oils form practically no vapors at 

 atmospheric pressure and temperature; 

 therefore, it is necessary to heat and boil 

 crude petroleum in a closed vessel, in 

 order to accomjilish complete vaporiza- 

 tion and separation of the ditTcrent 

 hydro-carbons. Since crude oil is a 

 complex mixture of hydro-carbons, each 

 of which has a different boiling point, a 

 different temperature is required for the 

 \aporization of each compound. Dis- 

 soKed gas and the lightest h>dro-carbons 

 pa.ss o\cr first, and as the temperature is 

 increased, heaxier and heaxier hydro- 

 carbons are xaporizcd. 



Re\erling to Figure I : llu' \apors 

 formed are led through a pipe from the 

 still and discharged into the base of an 

 aerial tower condenser. From there they 



