US2303023A - Process for producing improved asphalts - Google Patents

Description

caws an. A26a/Duyn /mer l v H. E. cir-:R vPRocEss Fon PRoDUcING lmrnovn APHALTs l y 3 Shts-Sxeet 1* y Filed D ec. 19, 1940 Fior N y ou. aufm IME tcPANl A. .STA/PPAA/ Patented Nov. 24, 1942 i I l g e l UNITED STATES PATENT OFFICE PROCESS Fort PRODUCING iMPRovED AsPnALTs e Harry E. Cier, Baytown, Tex., assignor to Standard Oil Development Company, a corporation ofl Delaware Application December 19, 1940, Serial No. 370,774 s claims. (ci. 19evii This invention relates to a process for produc- `The relationship existing between the penetraing improved asphalts and more particularly, the tion and softening point may be expressed by the invention is concerned with the production of equation 1 n asphalts having improved susceptibilities to tem- M=7tPa pe'iiizurireiaerlilyeniasrs different ,gi'adeseof4 asphalts Ymere M is the Ieg and bau softening point in have been prepared by blending asphalts of low del" P'ee peneatlen and falnd k eielgonses penetration with naphthas, gas oils, and heavier tepen nlg en e seuree e e asp. a .an k e fluxing agents. In fact, it is customary practice elerauetet .Whleh .the peeeelretmn l. te lele in the asphalt industry to prepare intermediate w existil g1 tvyenmfx 1S atrm arte?? @ning grades of asphalts by inuxing a natural or oxis b 1% F31 1e Y etpen 27513232' I dized asphalt with a suitable blend stock to prouy e 15.0. .vlseesl y e t measures duce an asphalt of proper specifications. It is e suseep lblhty ofthe asphalt te eonelsteney also well known in the art to dilute a crude changes et .elevated tempelfaturee Whereas ehe residuum with a liquefied normally gaseous 5 seftenmg pemt'penetratleeleeex 1s an. mdleetlen hydrocarbon and, by proper adjustment of term of the temperature susceptibility of an asphalt at perature, to throw out or precipitate from the oil nelgeal temera'uresg'z. F') '1 t y solution an asphalt which is suitable, after ux- 1s an e Jee. ef 1S meen len o pro uee en ing with a lighter oil or` asphalt, for use in road asphalt that Wm net eeftee te a great degree when used as a filler in either wood or stone zo f building or in manufacture of other material for block pavement. An *asphalt that Win soften which asphalt has been adapted' under normal summer conditions and which will Propane precipitated asphalts when blended to Deze out of. the jointsronto the paving blocks is f designation D5-25. The softening point, by the 'flgcormy rllltgggg lcltfg; nndesirabie and ,ebieetionabid It is a 'further and uxmg method it is possible to produce a 5 obiect of this invention to produce an asphalt wide range of products However these conventhat While neem net soften and eV under-usual tionally produced asphalts frequently have a high Lbellemcllgsleeielrt lggdmerasuz' softening peint'penetration index and a reletvely `mixtures and in road urfaciig compolitilon ggvrldlgr llgals gclaggl E'igl gierl 30 where it is necessary that the aggregate be coated with binder to produce a coherent adhesive` mass.

point-penetration and fluidity indexes, since one It has now been discovered that if a crude re index indicates the consistency at normal temperatures Whereas the other index is a measure .sldlm 1511 medgth e heavy O11 flletlen end of consistency at elevated temperatures.` In 1S en d1 u e W1 propane.' en .esp en of. 1m' Short these indexes for asphalt may be Compared 35 proved temperature susceptibility characteristics to the viscosity index for lube oils. The softenlgebamgt ggg lglrf ttlat ephellts ing point-penetration and iluidityindexes are dep 5ft t. g t1 1 .p 1er e p .0' scribed by Holmes, Collins and Child (Measur pane preelpl e' len are Vas y Supener le quality ing the susceptibility of asphalt to temperature to asphalts proqud by propane preclpfatlon changes H01mes Collins and Child, mi & Eng* do followedby uxmg. For asphalts of equivalent Chemistry Analytical Edition, vol. 8-pages 100- penetratlon thls product produced m the man' 104 Marcil 15 1936) who arbitrarily assigned a ner Which will be further described in detail, has Vahle of 100 for asphalts from Mexican crude and higher susceptibility vindexes than are obtained either by conventional propane precipitation or 0 for asphalts from cracking coil tar.

The softening pointmenetmtion indexs a re1a .n by conventional propane precipitation followed tionship existing Vbetween the penetration of an by uxirng- In general this invention H lay be deasphalt at '77 F. and the ring and ball softening SCllbed' as fOllOWSt a crude pe'rOleum is reduced point. The method ef test for determining the by dstlllalpn t0 a resldwm hai/mg a mmimum penetration of an asphalt is described in the 1939 Saybolt UnlVerSal VSCOSIY 0f about 400 Seconds Book of A. s. T. M. standardsincluding Tenta- 5f) at 210 F. While it is preferred to reduce the tive standards, Part, 111, under the A, S T, M crude to what is termed in the art a short residuum, 4it may also be reduced to along rering and ball method, is also described in the siduum. After reducing the crude to the miniaforementioned reference under A. S. T. M. desigmumy viscosity required the residual Crude may nation E28-39T. be uxedwth a lubricating oil fraction which fractions which will allow precipitation of asphalt from solutions thereof may be employed. The propane-oil solution is cooled to a temperature where asphalt and resinous material will precipitate and is then introduced into a suitable settling drum where asphaltic and resinous material separate from the solution as a bottom layer. The asphalt is drawn olf from the soluble oil and propane layer, may be washed with additionalamounts of propane, and is then stripped of residual solvent. The solvent-free asphalt is then suitable for use in road building or otherwise as may be desired.

' In the accompanying drawings, Figure 1 represents a general ow diagram of the process; Figure 2v a softening point-penetration graph; and Figure 3 a furol viscosity-penetration graph. With reference to Figure 1 which represents a now diagram of one embodiment of this invention, a heavy lubricating oil flux is introduced through line 2 into line I through which a crude oil residuum fraction is being charged by means of a pump not shown. The two oils are thoroughly mixed in incorporator 3 and are then heated to between about 120 F'. to 180 F. in heating means 4. The heated fluxed residuum is then diluted withV liquid propane which is introduced through lilies I9 and 20; make-up propane, when needed,

may be injected into the system through line I8. The fluxed oil and propane are thoroughly mixed in incorporator 5 and the temperature of the resulting propane-oil solution is adjusted to about 110 F. to 150 F. in heat exchanger 6 from whence the mixture flows into asphalt seti tler 1 which is preferably maintained at a temperature of about 110 to 130 F. However, the temperature of the asphalt in the settler may be maintained either higher or lower than the limits mentioned since the penetration of the precipitated asphalt is controlled by the precipitation temperature in the asphalt settler. An oilypropane solution is drawn off of settler 1 by means of line 8 into propane stripper 9 where solvent and lubricating oil are recovered. Vaporized propane from stripper 9 is returned to the system through line I0, liquecation means I2, and line I9. Deasphalted lubricating oil is drawn olf of the bottom of stripper 9 through line Il to storage. Asphalt is drawn olf of the bottom of settler 1, through line I3, into propane Stripper I4 where the asphalt is stripped of residual propane, the propane stripped from the asphalt being recycled to the charge system by means of line I5, liquecation means I1, and line 20. Asphalt of improved quality is drawn off to storage from the bottom of stripper I4 through line I6.

Although the mechanism of the solvent action, resulting in the improvement in asphalt temperature susceptibilities, Wrought by fluxing of postulated that by fiuxing the crude residuum prior to propane precipitation, poor fractionation between the predominantly oily and the predominantly asphaltic constituents occurs. This is a desirable rather than an undesirable condition, since it is further theorized that the undesirable components in the oil or asphalt employed as a uxing medium, which normally impart poor susceptibility t0 the mixture, are dissolved in the solvent, whereas those components which contribute toward good susceptibility are included with the precipitated asphalt. Thus, in eiect according to these theories, the ratio of oils to resins in the asphalt produced in accordance with this invention has been increased over that contained in asphalt produced by conventional propane. precipitation followed by uxing. It is to be clearly understood, however, that this invention is not to be limited by any theories which may be advanced in explanation of the improved result.

In order to more clearly describe this invention, reference is made to the following examples:

Example 1 Asample of' crude oil from the Pearsall field in Texas was reduced by distillation to 34.3%

bottoms. 'I'his residual fraction from the crude had the following characteristics:

Specific gravity at F 1.005 Open cup flash, F 610 Furol viscosity at 275 F 91 Pen. at77 F., 100 g.,.5 sec 232 Ring and ball softening point, F 104 Ductility at 77 F'. 110+ Solubility in C014 99.69 Oliensis test Negative The 34.3% bottoms fraction having the above inspection characteristics was subjected to a series of deasphalting treats in which one volume of reduced crude to four volumes of propane of 96% minimum. purity was employed. Temperatures between 120 F.. and 140 F'. were employed in the treats. The asphalt obtained from these treats were tested and the following inspection data were obtained:

Treat l Treat 2 Treat 3 Deasphaltng temp., F 120 130 140 Asphalt yield, Ywt. por cent on charge-- 69. 6 70. 4 82. G Specific gravity at 60 F 1.050 l. 025 1.034 Open cup flash, F 615 620 G15 Furol viscosity at 275 F 381 280 101 Pen. at 77 F., 100 gms., 5 sec 32 41 60 Ring 'and ball softening point, F-. 135 128 122 Ducniipy ai 77 F 110+ 11o-I 110+ Solubility 1n C014, per cent 09. 57 99. 73 99. 74 Oliensis test Neg Neg. N cg.

The sample of Pearsall crude residuum representing 34.3% bottoms on the original crude was then fluxed with a fraction from the same crude representing a 42-65.'7% fraction. The blended residual fraction representing 58% bottoms on the.- crude had the following inspection characteristics:

Specic gravity at '77 F 0.958 Open cup ash, F 385 Furol viscosity at 122 F 572 Per cent asphalt of penetration '74.8

'I'he fluxed bottoms fraction having the abovedescribed physical characteristics was also subjected to a series of deasphalting treats in which one volume offluxed reduced crude to four volumes of propane was employed. The propane diluent ranged between 87.4 and 96% by volume minimum purity. Distillation analyses rof the propane diluent showed the yimpurities to consist mainly of ethane and a small quantity of butanes. Thus for example, the analysis of the 87.4% propane diluent was as follows: Ethane 12.4%, propane 87.4%, butanes 0.2%. atures between 120 F. and 140 F. were employed in the propane precipitation of asphalt. The asphalts obtained from the treats of the iiuxed residual fraction were tested and were found to have the followmg charactenstics: l

Treat 4 Treat 5 Treat 6 Treat 7 Treat 8 Deasphalting temp., F 120 140 120 130 140 Asphalt yield, wt. per

cent based on charge 40. 5 46. 0 38. 5 39. 5 45. 5 Specific gravity at 60 F. 1.035 1. 019- 1. 042 1. 033 1. 041 Open cup flash, "F 425 425 420 425 430 Furol viscosity at 275 F. 339 127 320 269 222 Pen. at 77 F., 100 gms.,

5 SBC 48 165 41 66 77 Ring and ball softening 2 point, F 13o 1u 133 126 123 0 Ductility at 77 F 110+ 110+ 110+ 110+ 110+ Solubility in C014, per

cent 99. 75 99. 74 99. 67 99. 62 Olicnsis test Neg. Neg. Neg Neg. Neg.

Temper- 5 Child, fluidity indexes for asphalts having 50, 100, 150, and 200 penetration were obtained.

Fluidity index 9 C Ashalti f, onvenpro uce Irenetratlon at77 F. tonauy in accord produced ance with asphalt this (treats 1-3) invention (treats 4-8) On comparing the physical properties, as measured by softening point-penetration and fluidity indexes, of asphalt produced in accordance with this invention with that produced by conventional propane precipitation, it is readily apparent that this improved process produces asphalts of greatly improved temperature susceptibility characteristics.

` Example 2 It will be noted on comparing the data obtained on the asphalt from treat 2 with that from treat 6 that, for an equivalent penetration, the flash on the asphalt obtained in treat 6 is 200 F. lower than that obtained in treat 2 indicating that this asphalt contains lighter material than the asphalt from treat 2. It is this lighter material which imparts the desired temperature susceptibility qualities which are readily apparent from a further study of the data.

The softening point and penetration data obtained in treats 1 to 7 were then plotted on 2 cycle logarithmic graph paper with the ordinate representing the ring and ball" softening point and the abscissa representing penetration at 77 F. These data are presented graphically in Fig- Softening pointpenetration index Asphalt Penetration at 77 F. Convenproduced tionally in accordproduced ance with asphalt this (treats 1-3) invention (treats 4-8) 62 89 80 11o fc5 85 130 100 150+ In a similar manner, the furol viscosity of the asphalts from the several aforementioned treats were plotted as ordinates on logarithmic graph paper against penetration at 77 F. as the abscissa. These data are presented graphically in Figure 3. Then by recourse to the Fluidity index chart also constructed by Holmes, Collins, and 7A A residual fraction representing 34.3% bottoms on Pearsall crude was deasphalted at 120 F. employing four volumes of propane to one volume of the bottoms fraction. The resulting asphalt, which corresponds to that obtained in treat 1 shown in Example 1, was then uxed with a light motor oil to produce asphalts of different penetrations.

Blend 1 Blend 2 Blend 3 Asphalt, wt. percent 100 95 92. 5 Light motor oil, wt. percent. 5 7. 5 Furol viscosity at 275 F-.. 381 229 182 Pen. at 77 F., 100 gms, 5 sec 32 57 72 Ringand ball softening point, F. 135 125 121 The softening point and penetration data. obtained on inspections of the blends was then plotted on logarithmic graph paper and are Sotening point-penc tration index Asphalt produced by propane precipitation and Asphalt produced in accordance with this invention Penetration at 77 F.

On comparing the data in Example 1 with the `above results it will be noted that identical values were obtained by conventional propane precipitation and by propane precipitation followed by iiuxing. 'I'he asphalts produced in accordance with this invention, i. propane precipitation, however, are superior in temperature susceptibility (as measured by the softening point-penetration index) to either of the two conventional methods. Similar advantages are shown for asphalts obtained by my ime., fluxing followed byV proved method Whenuidity indexes are compared.

Example 3 A residual fraction representing 34.3% bottoms on Pearsall crude was blended with equal volumes of a light motor oil. Inspection characteristics of the Pearsall bottoms fraction are shown in Example 1. The light motor oil Was tested and had the following characteristics:

Specific gravity 0. 8783 Open cup ash, "F 450 Open cup fire, "F 530 SSU viscosity at 210 F 50. 3

Asphalt Asphalt precipitated precipitated at 120 F. at 140 F.

Furol viscosity at 275.o F 924 574 Peu. at 77F., 10() gms., 5 scc.. 17 28 Ring and ball softening point, F. 153 142 Open cupflash,F 520 525 These data were then plotted on Figures 2 and 3 to which reference has been made. The softening points were plotted as ordinates and the penetrations as abscissae on Figure 2. It Will be noted that these data follow the curve plotted from the data on asphalt obtained from treats 4 to 8 in Example 1.

In a similar manner, the furol viscosities at 275 F. Were plotted against penetrations on.

Figure 3. It will again be noted that the data follow the curve for the asphalts precipitated in treats 4 to 8 rather than the curve for asphalts from treats 1 to 3 presented in Example 1.

These data demonstrate that asphalts of superior temperature susceptibility may be produced in accordance with this invention of fluxing the residuum prior to propane precipitation rather than afterwards. The data also clearly show that the ux need not be a vcontiguous fraction of the same crude from which the asphalt is obtained. This is important since it may be desirable in some instances to flux the residual fraction with a low grade product for which no ready market exists.

I claim:

1. Process for producing asphalts having improved susceptibility characteristics to temperature changes comprising the steps of uxing a reduced crude with a loW viscosity hydrocarbon fraction boiling Within the lubricating oil range, diluting with a liquefied gaseous hydrocarbon, adjusting the temperature so that an asphalt is precipitated therefrom, separating said precipitated asphalt from that portion soluble in the diluent and stripping said precipitated asphalt free of light hydrocarbons.

2. Process for producing asphalts having improved susceptibility characteristics to temperature changes comprising the steps of iiuxing a reduced crude with a low viscosity hydrocarbon fraction boiling Within the lubricating oil range, diluting said iiuxed reduced crude fraction with a liquefied normally gaseous hydrocarbon, adjusting the temperature of said diluted, uXed reduced crude fraction so that an asphalt is precipitated therefrom, separating said precipitated asphalt from that portion of the uxed reduced crude fraction soluble in the diluent, freeing said separated asphalt of entrained oil fractions by Washing same with additional quantities of liqueed normally gaseous hydrocarbon solvent, stripping said washed asphalt free of light hydrocarbons in a stripping still, and recovering therefrom an asphalt of improved temperature susceptibility characteristics.

3. Process in accordance with claim 2 in which the liquefied normally gaseous hydrocarbon is propane.

4. Process in accordance with claim 2 in which the fluxing agent is blended with the residual crude fraction in the ratio of 0.2-2.5 volumes of uX to one volume of residual crude fraction.

5. Process in accordance With claim 2 in which the fluxing agent is an unfinished lubricating oil fraction.

6. Process for producing asphalt having improved susceptibility characteristics to temperature changes Which comprises the step of reducing a crude to a minimum Saybolt Universal viscosity of about 400 seconds at 210 fiuxing the reduced crude with a low viscosity hydrocarbon fraction boiling Within the lubricating oil range, diluting With a liqueiied gaseous hydrocarbon, adjusting the temperature so that an asphalt is precipitated therefrom, separating said precipitated asphalt from that portion soluble in the diluent and stripping said precipitated asphalt free of light hydrocarbons.

7. Process of producing asphalt having improved susceptibility characteristics to temperature changes Which comprises the steps of reducing the crude to a minimum Saybolt Universal viscosity of about 400 seconds at 210 F., fluxing the reduced crude With a low viscosity hydrocarf bon fraction of the same crude boiling within the lubricating oil range, diluting with a liqueed gaseous hydrocarbon, adjusting the temperature so that an asphalt is precipitated therefrom, separating said precipitated asphalt from that portion soluble in the diluent and stripping said precipitated asphalt free of light hydrocarbons.

8. Process of producing asphalt having improved susceptibility characteristics to temperature changes which comprises the steps of reducing by distillation an asphaltic crude to a residuum having a minimum Saybolt Universal viscosity of about 400 seconds at 210 F., uxing the residuum with a low viscosity hydrocarbon of a diierent crude boiling Within the lubricating oil range, diluting said fluXed reduced residuum with a liquefied normally gaseous hydrocarbon, adjusting the temperature so that an asphalt is precipitated therefrom, separating said precipitated asphalt from that portion soluble in the diluent and stripping said precipitated asphalt free of light hydrocarbons.

HARRY E. CIER.

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