Comparison of Platforming and Thermal Reforming VLADIMIR HAENSEL and MELVIN J. STERBA
Downloaded by MONASH UNIV on October 29, 2012 | http://pubs.acs.org Publication Date: January 1, 1951 | doi: 10.1021/ba-1951-0005.ch007
Universal Oil Products Co., Riverside, Ill.
A comparison has been made of Platforming and of thermal reforming from the standpoint of yield -octane number relationships, product properties, hydrocarbon types, and with respect to the nature of chemical reactions responsible for improvement of octane number. Comparison is based on studies of thermal reforming in a commercial operation at a Pennsylvania refinery and in a pilot plant on a mid -continent naphtha; and in pilot plants and laboratory Platforming on the same stocks.
T w o methods of upgrading straight-run gasolines are Platforming a n d thermal r e forming. P k t f o r m i n g utilizes a supported platinum catalyst and is conducted i n the presence of recycled hydrogen. Thermal reforming employs heat and pressure. T h e comparison i n this study is made on the basis of product distribution, hydrocarbon-type analysis, and yield-octane relationship. Because thermal reforming, i n many instances, is carried out i n conjunction with polymerization of the gaseous by-products of the operation, the comparison has been extended to a yield-octane relationship including the polymerization step following thermal reforming.
Thermal Reforming Thermal reforming of virgin gasoline fractions for octane number improvement had become a n established commercial refining tool i n the early thirties (4, 8, lJf). Essential features of the process flow i n use today do not differ markedly from those employed i n those early plants. I n 1933, Egloff and Nelson (4) pointed out that i n certain instances some advantages were obtained b y removing the high octane number light ends of a virgin gasoline b y prefractionation, and reforming only the heavier low octane number naphtha. T h e y also pointed out that, as the octane number of the final blended product is increased, a point is eventually reached where the advantage of prefractionation disappears. I t then becomes more economical to reform the entire gasoline. Egloff, Nelson, a n d Z i m merman (S) present experimental data to illustrate these points. Correlations presented i n the middle thirties enabled the prediction of octane number improvement resulting from thermal reforming (7, 21). T h e y have continued to appear i n the literature (6, 20). Improvement of the octane number of naphthas has been the principal function of thermal reforming, but Egloff (3) discusses its usefulness also for the production of light olefins which provide feed stocks for alkylation or polymerization processes. T o show the distinct improvement i n the yield-octane relationship realized b y the catalytic polymerization of C and C olefins produced by thermal reforming, Mase a n d Turner (16) present experimental data at various reforming severities for two naphthas. Because the octane number of straight-run gasoline can be improved to a certain extent b y either a process involving chemical change or b y the addition of tetraethyllead, 3
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In PROGRESS IN PETROLEUM TECHNOLOGY; Advances in Chemistry; American Chemical Society: Washington, DC, 1951.
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HAENSEL AND STERBA—COMPARISON OF PLATFORMING AND THERMAL REFORMING
Downloaded by MONASH UNIV on October 29, 2012 | http://pubs.acs.org Publication Date: January 1, 1951 | doi: 10.1021/ba-1951-0005.ch007
the refiner must establish the optimum extent of each operation producing the desired octane number at minimum expense. Economical appraisal of thermal reforming and tetraethyllead addition for octane improvement was discussed i n an early paper b y G a r y and Adams (7), and more recently b y Feuchter (6). The economics of thermal reforming and hydroforming of sweet and sour heavy straight-run naphthas have been compared recently b y M c L a u r i n , M c i n t o s h , and K a u f man (16). They concluded that the relative economics of the two processes were v i r t u ally the same for both feed stocks. M o s t thermal reforming operations are performed a t cracking coil transfer temperatures i n excess of 1000° F . , and at transfer pressures i n the range of 500 to 1000 pounds per square inch. Equipment following the cracking heater resolves the heater effluent into a residuum, gasoline, and appropriate light hydrocarbon fractions. Often this fractionation equipment is common with other thermal cracking processes i n the refinery. I n a few instances straight-run gasolines are charged with light recycle to the light oil coil of two-coil thermal cracking units i n order to accomplish mild reforming.
Platforming Since the announcement of the Universal O i l Products C o . Platforming process i n A p r i l 1949 {17), a number of publications (1, 2, 9-13, 19) have described the operating variables and chemistry of the process. Particular features of the Platforming process involve use of a platinum catalyst and the recycling of a hydrogen-rich gas. The following reactions take place i n Platforming: dehydrogenation, hydrocracking, isomerization, desulfurization, dehydrocyclization. These reactions are relatively selective i n character, so that high yields of high octane fuels can be realized. Furthermore, these reactions can be made to proceed to different extents, so that fuels of variable aromaticity and volatility can be produced. A basic reason for this is the relatively low temperature of operation employed i n Platforming, permitting the elimination of undesirable thermal decomposition effects. I n view of the number of reactions that take place, the process is not limited to selected charging stocks. A highly naphthenic stock is upgraded largely b y the production of Table I.
Commercial Thermal Reforming of Pennsylvania Gasoline Inspections of Feed and Liquid Products Straight-Run Gasoline Charge DebuAs received tanized
API Total sulfur, wt. % Mercaptan sulfur, wt. % Reid vapor pressure Bromine number Octane No. F - l clear F - l + 3 ml. T E L / g a l . F-2 clear F-2 + 3 ml. T E L / g a l . Viscosity, S.U.S. at 210° F . 100 ml. distillation Initial boiling point, ° F . 5% 10 30 50 70 90 05 E n d point % recovered % bottoms % loss Light hydrocarbon content, vol. % CaHe C4H8 C4H10
Total C« C.+
Debutanized Thermal Reformate
Laboratory
Blend of Thermal Reformate and Polymer Gasoline DebuAs proResiduum duced tanized
63.6 0.07 0.004 10.3
60.7 0.07 0.0068 3.1
57.8 0.06
62.1 0.06 0.014 12.4 52.0
58.1 0.07 0.0107 4.4 60.3
50.7 70.2 49.8 68.9
44.4 65.2 43.9 64.4
77.3 89.0 69.2 80.6
82.4 91.2 75.1 83.2
80.0 89.9 72.2 81.1
12.5 0.06
50.2 96 137 159 217 255 294 345 370 389 96.5 1.2 2.3 1.5 5.5 8.5 84.5
128 167 180 220 254 292 336 355 384 . 98.5 ' 1.2 0.3
124 147 155 186 227 273 327 354 385 98.0 1.0 1.0
93 122 137 180 224 269 342 384 402 96.5 1.2 2.3
123 151 161 193 229 270 332 361 403 98.5 1.2 0.3
0.8 2.7 7.0 13.5 76.0
In PROGRESS IN PETROLEUM TECHNOLOGY; Advances in Chemistry; American Chemical Society: Washington, DC, 1951.
268 463 512 585 634 671 727
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Table II.
ADVANCES IN CHEMISTRY SERIES
Over-all Material Balance on Thermal Reformer and Polymerization Unit Bbl./Day
Vol.%
°API
Lb./Hour
Wt. %
Straight-run gasoline charge
1683
100.0
63.6
17,779
100.0
Products Total fuel gas (37,635 standard cu. ft./hour) Reformate + polymer blend (12.4 lb. R V P ) Residuum
1333 20
79.2 1.2
62.1 12.5
2,904 14,194 286
16.3 79.8 1.6
17,384
97.7
Product recovery
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