148 



National Resources Planning Board 



of gasoline, ulllioiif;li later it was fuuiid that these 

 properties profoundly influence the performance of the 

 naphtha fractions in the internal combustion engine. 

 However, the discovery that it was possible by thermal 

 treatment to break down the high molecular weight 

 fractions into compounds boiling in the gasoline range 

 pointed tlie way to a solution of the problem of pro- 

 ducing additional motor fuel of improved quality. 



In attemi)ting to trace the developments that have 

 taken place during the last two decades it is difficult to 



consider the petroleum and automotive industries 

 separately, as there is not always a clear distinction 

 between which was cause and which effect. Both 

 industries can perhaps best be thought to have devel- 

 oped along parallel lines, as neither could have reached 

 its present state of development without the impetus 

 provided by the other. At any rate, it was the prob- 

 lems which arose from the development of the indus- 

 tries jointly, more than any other contributing factor, 

 that forced the petroleum industrj' into research on the 

 chemistry of its raw materials, products, and processes 

 and on the chemical engineering operations involved. 

 Out of the research have come our modern cracking 

 operations which are capable of raising the yield of 

 gasoline on crude oil from an average of some 20 per- 

 cent to more nearly G5-75 percent. Actually, a lower 

 average figure of about 46 percent is currently being 

 realized country-wide because of the demand for higher 

 boiling fractions, notably in the form of the various 

 types of fuel oils, kerosene, and lubricating oils. The 

 increase in gasoline yield produced by cracking over a 

 number of years is illustrated in figiu-e 35. 



A comparison of the trend shown in figiire 35 with the 

 curve for gasoline production in figure 36 gives an idea 

 of the vast scale on which the cracking operations are 

 being carried out to supply the current demand for 

 motor fuel. Considering that cracking is an operation 

 which is being carried out at temperatures ranging 

 from 850° to 1,200° F. and pressures extending to 1,000 

 pounds per square inch or more, one may realize the 

 jiroblems involved in equipment design and operation. 

 Tiie early cracking units of 25 years ago were capable 

 of handling only a few hundred barrels of charging 



PERCENT 

 {ON CRUDE) 

 28 1 



y 



7 



^: 



STRAIGHT RUN 



^ 



y 



A 



/ 



/. 



FiocRE 34. — Experimental Oil Cracking Still, Gulf Research 

 and Development Company, Harmarville, Pennsylvania 



Figure 35. — Variations in the Consumption of Straight Run, 

 Cracked, and Natural Gasolines in Terms of Percentages of 

 Crude Oil, 1921-39 



