Oxidizing Towers .4re Heart of Lion Oil Company’s Asphalt Plant
A Stafbladuatry C o b b o r a t i v e Report WILL H. SHEARON, JR. Managing Editor
A
in collaboration with
LMOST 13,000,000 short tons of petroleum asphalt were
produced in the United States in 1951. Of this amount 70% was used for paving. Specialty applications accounted for only 5y0 of the total. These latter applications are growing in both variety and quaitity used, but asphalt, known and used by man in building since the earliest recorded times, is essentially a “forgotten” plastic in these days of attention to the remarkable monomeric and polymeric chemicals which are being made industrially. True, asphalt can be used to make but a few of the molded or cast products which we generally associate with the designation “plastic wares.” However, the flow properties of asphalt combined with chemical inertness, water impermeability, and high durability place it high in consideration for specialized uses where plastic properties are required. That asphalt is finally being recognized as a plastic is evidenced by the fact that one scientific publishing house has placed a new book on asphaltic bitumen properties ( I O ) in its Polymer Series. Perhaps one of the most important reasons for the failure t o stress asphalt use where certain plastic properties are desired can be laid to our general ignorance of the material. In the recent “Symposium on Unsolved Problems in the Petroleum Industry” ( S ) , it was pointed out that about all we know, even at this time, concerning the composition of asphalt and its rather arbitrary separation into asphaltenes, petrolenes, and the like,
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ARNOLD J. HOIBERG lion Oil Co., El Dorado, Ark.
is that the molecular weight and the carbon-hydrogen ratio are very high. We are not even sure whether these materials should be classed as hydrocarbons, sulfur compounds, or oxygen compounds. There is even a good hit of disagreement on the subject of molecular weights, because widely differing results are obtained by cryoscopic and ultracentrifuge and other methods. The wide differences in results are probably related to the sensitivity of the different methods to constituents of different particle size found in the asphaltenes, since this fraction is a mixture of compounds and can be further divided by solvent fractionation. Further, as long as asphalt has been knoan, even though much has been determined of the complex stress-strain-time behavior ( I O , IS),there are no standardized methods for predicting service behavior from measurements of fundamental flow properties. At the present time the Franklin Institute and the American Society for Testing Materials have programs under n a y with the object of developing simple but fundamental laboratory flow tests that are capable of being con elated with service requirements of asphalts. Asphalts as a class are nonaqueous colloidal systems of very high viscosity, which may have the character of either a sol or a gel. They consist principally of hydrocarbons and hydrocarbon derivativep and may contain groups of saturated aliphatics, naphthenics or cycloparaffins, aliphatics with olefinic double
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 10
I
Trade Glossary Asphalt = Black to dark-brown B~lidor semisolid cementitioua material which gradually liquefies when heated; its predominating constituents are bitumens, all of which occur in the solid or semisolid form in nature, or are obtained by refining petroleum, or are combinations of the bitumens mentioned with each other or with petroleum or derivatives thereof. hphalteues = The components of the bitumen in petroleums, petroleum products, malthas, asphalt cements, and solid native bitumens, which are soluble in carbon disulfide but insoluble in p a r a h naphthas. Bitumens = Mixtures of hydrocarbons of natural or pymgenous origin or combinations of both frequently accompanied by their noumetallic derivatives, which may be gaseous, liquid, semieolid, or solid and which are completely soluble in C&. Carbenes = The components of the bitumen in petroleums, petroleum products, malthas, asphalt cements, and solid native bitumens, which are soluble in C& but insoluble io CCI,. Cutback = Aaphalt to which a solvent such as petroleum naphtha haa been added, usually to reduce the application temperature.
bonds, and smmatics (IO). Classified another way, they consist of high molecular weight portions termed aaphaltenes and petrolenes. This latter fraction is often separated into resins, waxes, and oils. The resins and waxes are soluble in the oils and form the continuous phase of the colloidal system, with the resina acting as the dispersing agents and the aspbaltenes as the colloids. Air Mowing Provides Wide Variety oi AsRhaH Produrn
, *,
Petroleum asphalt production haa up until a few years ago been characterized according to production method-cracked, straight-run, or air-blown. Cracked asphalts have been limited in their uses because of extreme changes in viecosity with temperature change and low oxidation resistance, and as thermal cracking proceases are replaced by catalytic cracking in refineries, c m k e d asphalts from the &her& processes will become increasingly less important. Straight-run amhalt. made bv distilling offthe lighter~fractionaof a ;rude oil to produce a &due of predetermined penetration containing the heaviest compounds in the chnrge, is a large volume material, and a typical Plant for its production was described in this journal by Kastens (8).
Air blowing qf asphalts, begun largely to harden flux oils to paving asphalts, provides a wide variety of end products not obtainable b other processing. Air blowing of asphalts results in increased Lrdneen, gravity and softenin point and lower ductility, with the extent of these changes aependin on the ariginal asphalt and the proceffiing and oxidation to w%ch i t is subjected. Figure 1shows the relationship between penetration and aofteniog point values for air blowing and for &stillation; some properties of asphalts of interest in industrial applications are ‘venin TableI. Tfe s u g y t e d use of added agents in air blowin bitumen is even oder than the air blowing of crude residua, but it was only a qusrter-centur a%o that recognition wss given to the fact that the use of sByt8 such 88 ferric chloride, in addition to acceleratin the blowing reaction, would produce asphalts of greater flexi%ilityat low temperatures and increased
03
odober 1953
Fluxes
= Asphaltic residua softer than 300 peuetration, uaed in cornhination with asphalts for the purpose of softening the latter or air-blown to roofing and other asphalts. Petmleae = The asphaltene- and carbeue-free fraction from asphalts. Ductility = As a property of asphalts, the ductility is expressed as the maximum number of centimeters which a test specimen will stretch without breaking. Float Test = A test applied to semisolid bituminous materials by which is determined the time required for water to force bitumen from a collar fastened in a saucer and Boating in a bath at standard tsmperatures, usually 122” F. Penetration (of Bitaminom Material) = The consistency of bituminous material, expressed as the distance in mm./lO that a standard needle penetrates vertically into a sample of the material under known conditione of loading, time, and temperature. Softening Point = The temperature at which a& phalt is soft enough to permit 8 steel ball to drop through a disk of asphalt supported in a ring s w pended in water or glycerol (ring and ball method).
renistanve to flow at high temperawren. So little publicity bad been ‘veu air-blown asphalt produced with addiuon of a c a w lyst t f a t 5 years ago Kastens (8)wid, “Standard of Calionria . . . uroducinx ‘blown’ awhalt bv a catalvtic nrocesa at ite Richmond reline6 . . . is beli’wed 6 be the dnly producing catalytic kilowin unit in the Country.’’ Standard of California ucsa the ferric cfdoride method and its plant has been in operation about 10 vears. At the time of Ksstms’ writine however. Lion Oil Co.; one of the largest petroleum asphalt pr&cera, I d in operation at ita El D o d o Ark., refinery a commercial u?it for makin catalytic asphslt hy the use of pkosphorus pentomde catalyst (87, and Lion’s catalytic halt production today amounts to auwoldmstelv 1% of ita tosnmduction. This small uercentaae in due to tbe.faci-that Lion’sblani is completely out Of the g& graphiral area of musumption in principal application of the c a m tic asphalt--eanal Imine-and the company‘s liernaeen l a r d ~ a t i s f vthis demand. Table 11 shows a breakdownof p d u c t i o n &es on a national basis and for Lion. Lion oil CO. Uses %me Equipment for Air-Blown and Coblylic Asphalts al Its El Dorado, Ark., Refinery
Lion uses the s m e equipment for both its conventional aiF blown and its catalytic air-blown asphalts. Either process begins -4th a residuum 01 “flu*” from one of the crude oils. This residuum is steam- and/or vacuumreduced, and the selection of a particular baae is made wording to the service requirements desired in the product. Properties of the crude oils used and the typical residua from them are tabulated in an earlier description (la) of Lion’s protective coathga plant. Selection of a base with a 70’ to 13o’F. softening point will result in blown products of any desired softening point up to 4oooF. In addition t o these tanka for raw materials, cutback solvents, and h i s h e d products, there are nine tanka for blending. Three of these are 1COLLbarrel capacity, insulated, and with s t e m coils, for asphalt blending and storage; two similar ones are of 2ooo barrel capacity. For cutback blending there are two !900-haml tanka with steam coils and mixers, one 42O-barrel horizontal
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
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ENGINEERING AND PROCESS DEVELOPMENT ~
Table I .
Some Properties of Asphalts of Interest in Industrial Applications Residual, Straight-run (Uncracked) 20-300 100-150 0.99-1.05
Residual. Cracked
Oxidi7t.d Asphalts
5-300 100-200 1 05-1.20
5-200
100-400 0 99-1 10
0 00035 0.00038
0 . 0003Ra
0.00038~
0.0003.5 0 00038
0.39-0.41 0 48-0.48 0.55-0.57
0.36-0.39 0.42-0.46 0.50-0.55
0 38-0 41 0 45-0 48 0 54-0 57
0.094; .... 0.097d 0.086 0.083f 0.093J 10' a t 77' t o 9jo F. )(nini.j(hr.) for water vapor (ST. 3.0-9.3e 6 . 0-11.5 i 5.4h HT, 1 1 T ) i.j(hr.) for oxygen 0.4i o n ( 1 T ) (extrapolated values). % After 50 weeks 1 R-l0k S f t e r 100 Feeks 2 , .?-I 6 . 5 k Surface tension ( 9 T ) , dynes/cm 32tn At 77'F. 341 .... At 212O F. 291 28m .... Total surface energy (QT), ergs/sq. c m . 61 51 .... Dielentric strength (ZOT), plate ~lcctrodes,hv./mm. 2.5-351, At 20" C. 10->60n >6OQ At 50: C.
