US 2695264 A
Description (OCR text may contain errors)
Nov. 23, 1954 w. o. TAFF :TAL VISBREAKING OF HEAVY HYDROCARBONACEOUS MATERIA Fild Dee. 28, 1950 m. 1M E lmv mm Mw Hl l LD 5E T No 9 AW s .am i im W D .E E F p o C Q m M o L W n| bo L @c V .l 5. 9
y 2,695,264 Patented Nov. 23, 1954 VISBREAKING -OF I-IEA/"Y: HYDROCARBONA'- 5 CEQUSTMATERIALS:
Wilfred 0. Talr and John^Weiliart, Cranford, and Richard W; Eustis, Fanwood, N. J., assignorsto StandardOil Development Company, a corporation of Delaware Application-December 28,4- 1950,-Serial N o. Y203,112 I s Claims. (ci.Vv 1961-50) to 'a method of Vtreating 15 More specifically, the in vention pertains The present invention relates hydrocarbons.
In relningcrude'oihthe'first stepfisnormally a simple distillation orl topping to produce distillate fractions and "a heavy residue. In-orderto'obtain-rnaximum yields of high quality; motor fuels-, allffractions boiling above distillationboiling"above about 800i F: doesnot,A as such, represent a feed stock suitable forcatalytic-icrackm fatory catalytic cracking feedstocks from'these residues; viscosity reduction or visbreaking. is :one of the mostwidely used.
Visbreaking involves atreatment of reduced crude" or 45 the like at temperatures of about 780-950 F. and pres= suresof vaboutl -200-1500 p; -s.- i. g.V at *feedfrates of--1-75 volumes per hour of oil at 60 F.; per'cracking volume above 750 F. to produce bya mild'type of thermal: crackingrabout 5-'15 vola per -cent of gasoil, about 5 -15 vol. lper cent. of gasoline and about 85-70 volrpercent-'of 50 heavy 'fuel' oil. Specific :conditions 'Within'thef'ranges specified depend onrthe. type of the visbreaker'feed; The
fining. The presentinvention provides: anaoperation'of; this type.
It is, therefore, the principal object of this invention 75 to provide improved means -forvisbreakingvheavyfpetroleum residues lof the type specified, permitting the: production tof maximum yields Tof motorand distillate' fuels andrelatively small..yields. of ahighnualty. heavy, fuel'ioil.
the subsequent description of the invention whereinrefmore-severe than those of Other lobjects and advantages willzfappearvfrom l 80:
2 Y erence will benracle to the.acccunpanyingl drawing;.th`e s xngle .figure of which isl .a (semidiagrammatical illustra? tion of a1system-su-1tabletocarryout a preferred-,embodit hasrnowf been found that the-thermal Azcracking :sevof the*` visbreaking foperationmay; be.- substantially t hezzonejin' \vhichit'is separatedY` from hghtenvlsbreakerv products".v Tar..l temthe effluent of 'the visbreakingzone `from"visbreaking temperatures of .about'78`0'950` F; depending; onzthe type "of'feed'rto'a tempera-tureof about .500g-'800 F: prrorfto f Whenoperatng'in"this manner, the'gasolme -yield-fobtained-finvthe visbrea'king process vitself -rnayibe increasedy by abouti-'10%' on-'feed 'the same' n on feed-of high quality loWfsediment-fuel 1Aoil'. An increase inf'the gasolinefyieldfof 2.-'l-0%ffonifeedinay represent, depending on the type of feed, a 20-100% increase `in` gasoline yield. Visbreaking fori this purpose include temperatures of about 780- 950 F., pressures of about 200-1500 p. s. i. g. and visbreaker feed rates of 1-75 volumes per hour of oil at 60@ F. per cracking volume above 750 F. As in conconventional operation, with- 1n the ranges specified. Particularly, the temperature maybe about 20-50 F. higher than that conventionally used-for-the same feed,
typesuofnoperations,v when incorporated into the rprocess of the invention: The @tube i and tanlc type arrangement providing extensive"soakingsspaceifor the feed-.at Jvis'f` breaking .conditionsnafords definitely less significantim#y provements.
Having :setl'fortli its fobje'cts and general fnatureyf invention will be bestunderstood from'thefmor'edetailed description hereinafter read with refcrenceftofthefdraw ing.A The fsystem illustrated.y thedrawingfhessentially af-'a'shtower V15'fprovicledfwith a'tar pot "21 'and atar pot quench circuit 29, 33, 35. e functions and coaction ofi-these-elements will be presently described in connechydrocarbonaceous residues.
In operation, a virgin crude distillation residuum boiling3above about 800 F. may be supplied from line 1 by feed pump 3 via line 5 to visbreaking coil 7 substantially at the' temperature at which it is recovered from the crude still, sayrat about 500-750 F. Coil 7 is arranged in furnace: 9 in such a manner as to provide a preheating sectionfmaintained at about 700-850 F., a heating sec- Y 3 d tion maintained at about 780-950 F. and a relatively similar temperature distribution. Other modifications short soaking section maintained substantially at the within the spirit of the invention will appear to those temperature of the heating section. The feed is heated skilled in the art. in coil 7 to the temperatures mentioned in the order in The advantages afforded by the present invention will dlcated at a pressure of about 100-1500 p. s. 1. g. C011 5 be further illustrated by the following comparative exdmeusions and oil feed rate are so correlated that the perimental data Two different crude residua were oil residence time at visbreaking temperatures exceeding treated in a pilot plant designed and operated substan- 750 F. will be about 0.8-30 minutes, corresponding to tially as described above with reference to the drawing. an oil throughput of about 75-2 volumes of liquid oil per These feed stocks had the following inspections.
volume of visbreaking coil per hour (v./v./hr.). 10 Table I The visbroken product is withdrawn at visbreaking pressure and a temperature of about '780950 F. in mixed vapor-liquid phase via line 11 wherein it is preferably quenched to a temperature of about 500-800 F. by the addition of product tar from line 13. For this 15 Resduum Residuum A. B
purpose about 0.5-1.5 liquid volumes of product tar per GvitY, API liquid volume of residuum feed may be supplied through gsfsgrfggffog at 210 F 2g 43(1)?) line 13 at a temperature of about 400-650 F. as will Surinam,percent f f: 3 03 2, 71 appear more clearly hereinafter. The quenched product Conradson Carbon. wt. prcen 15.7 19.7 is flashed by means of pressure release valve 14 into a 20 10 mfgvcmm DStuaton 513 698 lower portion of the baled section of tiash tower 15 at 5%, i F 879 93o a temperature of about 450-800 F. and a pressure of FBP. F 948 948 Recovery, wt. percent 13. 0 7. 0
about 1D0-200 p. s. r. g. Stripping steam is admitted to flash tower 15 via lines 17 at a point below the feed point of line 11 to aid in the removal of distillate prod- 25 The tar recovered from the tar pot in each case was ucts including gasoline and gas oil which leave tower 15 blended to a constant Saybolt Furol viscosity of 175 overhead through line 19 to be further worked up in seconds at 122 F. with the same gas oil range iiux stock conventional fractionation and catalytic cracking equipin accordance with accepted conventional practice. ment, not shown. These fuel oil blends were then tested for their sedi- Heavy tar of a boiling range suitable for inclusion in ment characteristics by the same filtration procedure at heavy fuel oil is collected in tar pot 21 and handled the same conditions and the sediment removed was retherein as follows. Product tar is withdrawn via line 23 ported as weight percent. Fuel oil blends indicating and passed to storage at a rate of about (16S-0.95 liquid sediments in excess of .5% are considered unsatisfactory volumes per liquid volume of residuum feed, controlled from sedimentation characteristics. by valve 25 which is operated by conventional level con- 35 The visbreaking experiments were carried out at a trol means 27 such as conventional ball float or diiferenvisbreaking coil pressure of 350 p. s. i. g., a throughput tial pressure controllers. The tar level in tar pot 21 is of 15 v./v./hr. in the visbreaking coil section mantaine so adjusted that a substantially constant tar hold up and above 750 F. and a ash tower pressure of about l0() a tar residence time of about 0.5-5 minutes, preferably p. s. i. g. Other reaction conditions and the results obclosely approaching the lower limit, is provided at the tained using residuum A are tabulated below.
Table Il Quench to Line Flash Tower s d Ot Gasomeerit Run Temp., Rate Flash TM Pot lind .ggf F. Tenga, vxgif- Tzerltrrlie -f-- e neng ma F?" Tage gg' 1 ssn 796 794 19 15. s 1.8
residuum feed rates here specified. A stream of tar is Comparison of runs F and G indicates that run G which circulated from the bottom of tar pot 21 via line 29 by employed the lower tar pot temperature, 603 vs. 794
means of pump 31 through a cooler 33 and via line 3S F., and shorter time, l vs. 19 minutes, produced a fuel back into the tar pot Z1 at a point above the withdrawal oil of satisfactory sedimentation characteristics while run point of the circulating tar stream. The temperature of F with high temperature and long time conditions in the cooler 33 and the tar circulation rate through line 35 are 60 tar pot produced an unsatisfactory product. It has been so adjusted that the tar pot temperature is maintained previously stated that increased cracking severity deat about 400-650 F. This may be accomplished by grades fuel oil quality as to sediment but this does not circulating about 0.25-5 liquid volumes of tar per liquid qualify the results above since cracking severity as measvolume of product tar through line 35 at a temperature ured conventionally by gasoline yield is constant. In of about 2O0Jf50 F. A third tar stream may be with- 65 order to obtain a satisfactory fuel oil without using the drawn from tar pot 21 and passed through line 13 to process of the invention, the cracking severity and conline 11 to serve as the quenching medium in line 11 as version must be reduced and hence gasoline yields will described above. be reduced and heavy fuel oil yield increased.
The system of the drawing permits of various modi- Another example in which a residuum of diiferent lications. For example, the quench could be added at 70 character was used at the operating condition previously the flash zone rather than in the transfer line to provide cited is summarized in Table III below for residuum B.
Table III Quench to Line Flash Tower a/ Sedi- B 'r P t (iwnii/eilt ar o me Ilg Yield Per- Temp cent o F Tsnp., 'l/lime,
Q S 787 786 17 13. 7 (l) R.- 920 530 0. 77 605 530 1 13. 5 0. 42
1 Too high to be determined using this test procedure. Experiments indicate that this value is in the range of 1-2 0.
is, therefore, a preferred embodiment of the present invention.
It has also been found that superior feed stocks for the purposes of the invention compared to tube-and-tank procedures.
The foregoing description What is claimed is:
1. In the process of viscosity breaking heavy hydrocarbonaceous residues by a thermal treatment carried out at temperatures of about 780-950 F., pressures of about 200-1500 p. s. i. g. and treating times corresponding to feed rates of about 1-75 volumes per hour of feed of 60 F. per volume of reactor space above 750 F.
the improvement which comprises carrying out said treatzone at a temperature of about 400-600 F. said ashing temperature and for a residence time of about 0.5-5
and withdrawing distillate fractions from zone.
2. The process of claim 1 in which said material is quenched to a temperature of about 500-800 F. prior to dashing, by the addition of tar withdrawn from said collecting zone.
he process of claim 1 1'11 Which said collecting zone temperature and residence times are maintained within the lower brackets of the ranges specified.
References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,105,122 Kimball et al. Jan. 11, 1938 2,152,147 Nafsinger Mar. 28, 1939 2,187,708 Cibulka et al. Jan. 16, 1940 2,189,016 yMiller et al. Feb. 6, 1940 2,209,154 Downey `Iuly 23, 1940 2,358,150 Cooke Sept. 12, 1944 2,385,325 Bailey Sept. 25, 1945