US2341269A - Hydrocarbon conversion - Google Patents

Description

R. B. DAY ETAL HYDROCARBON CONVERSION Feb. s, 1944.

Filed Jan. 2l 1941 F /PC 770/1447 CA TAL V/c PEA/T0139 fw y, Z m/l m 7 M w 22 M E A 8 5 W mi V p w IY .Iv I 5 f5 w /e/ 9 r 4 w d il, 1 ltl Y 1v P MAN |1 /4 79() M DMW 4 7 7 w m MM L 1+ 7 w GM 4 5 2 WT n@ f 11.. A| PM QE g E; .m4 0 a X p mm l5 4 f S of@ rz 7 7 W M w ,o E M 5 H W L 8 4.11.1 iH E F -KTO 0 J a /s w www E Patented Feb. 8, `1944 a nrnnocanoN coiwlmsron Roland B. Day and' Elmer R. Kanhofer, Chicago, lll., assignors to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application January 21, 1941, serial No. 315,106- 'z claim.` (ci. 19o-sa) 'Il'his invention relates to improvements in the method of effecting conversion of hydrocarbon voil in as combination catalytic and pyrolytic cracking system in which relatively high yields ,of high octane rating gasoline are produced.

More specically the invention relates to im provements in the method of conducting the catalytic conversion' reaction and provides a more accurate means for controlling temperatures and space vvelocities in the catalytic conversion treatment.

In the catalytic cracking of hydrocarbons to N produce lower boiling products therefrom, it has been found that insufllciently converted hydrocarbons formed in the process contain relatively large quantities of cake forming hydrocarbons which are reduced tocoke ii returned to the catalytic crackingv step with no intermediate treatment for their removal or conversionv into hydrocarbons more vsusceptible to catalytic cracking. I

. yIt is noi` considered advisable to treat such insufficiently converted hydrocarbons from tatalytic cracking to rempve the carbon forming. constituents contained therein by solvent extraction, for example, but more generally by pyrolytic cracking. In the operations involving the pyrolytic treatment of the insumciently converted hydrocarbons from a catalytic cracking process wherein at least .j a portion` of the reaction products formed in the pyrolytic cracking step is supplied to the catalytic cracking step, it has been shown that the deposit of oarbonaceous substances on, the' catalyst is less in such cases for the same quantity of oil converted than in a once-through operation on'a virgin stock.. In the latter type of operation, however. relatively large quantities of gasoline this gasoline will ordinarily be from 1'0 to 15.

points lower in octane rating than that formed in the catalytic cracking step with the result that the octane ratingv of the nal blend of the two distillates formed in the two cracking steps is considerably below that which may be obtained' when`recycling all of the insufnciently convertedhydrocarbons direct to the catalytic sirable feature of high carbon deposition normally associated with such a process.

It has been found that the octane rating of improvement oi the octane rating of this material is probably due to an isomerizing effect, and although the conditions employed in the catalytic vcracking step are not optimum for the isomerizing reaction,' improved results are definitely shown. TheA relatively low liquid hourly space velocities employed in thecatalytic cracking step as compared to the higher space velocities desirable in the isomerizing reaction will cause an 4increased gas production when gasoline' boiling range hydrocarbons are returned to this step as compared to the gas production when the pyrolytically formed gasoline is separately treated.

In our invention. to obviate some 'of the undesirable features associated with the processes previously mentioned, we provide a catalyst zone separate from the initial catalyst cracking zone to which all of the conversion products from the catalytic cracking step plus the pyrolyticallyV formed gasoline is supplied whereby conditions in such separate zone may be controlled within the limits optimum for improving the octane 'rating of the pyrolytioally formed gasoline in the absence of any substantial amount ot crack`' ing to lighter products and coke. Preferably also and in accordance with .the objects of the invention, the pyrolytically formed gasoline with or without the separation ot light normally gaseous hydrocarbons is separately heated and the heated distillate thereafter commingled with the conversion products from the catalytic cracking step, the heating of such distillate being controlled so that the temperature oi the final mixture is optimum for the reaction to be accomplished. Thevolume o'f such separate cata ,lyst zones may be controlled within desirable limits so that the space velocities oi the hydroare formed in the pyrolytic cracking step and carbon reactants brought in contact with the lcatalyst contained therein are optimum -for the process.

In one embodiment the invention comprises subjecting a readily vaporizable hydrocarbon. oil

, to contact with a mass of cracking catalyst to cracking step neglecting in such cases the nudel the gasoline produced in the pyrolytic crackingstep may be improved by commingling such' gasoline with the stream of hydrocarbon oil to be converted in the catalyticcracking step. The

eifect conversion into lower boiling products, commingling the conversion products with fractionated 'vapors separated as hereinafter set forth and passing the mixture in Contact with a separate mass of cracking catalyst, fractionating thecomprise passing a readily vaporizable hydrocarbon oil heated to a cracking temperature in contact with a mass of cracking catalyst to effect conversion into lower boiling products, commingling the conversion products with fractionated vapors separated as hereinafter set forth and passing the resultant mixture in contact4 with a separate mass of cracking catalyst at a relatively higher space velocity thanthat employed in the rst mentioned mass, fractionatixr g, the resulting conversion products to separate fractionated vapors boiling substantially in the range of gasoline from insufilciently converted hydrocarbons, cooling and condensing vsaid fractionated vapors, subjecting said insufliciently converted hydrocarbons to pyrolytic conversion together with a diflcultly vaporizable hydrocarbon oil, fractionating vaporous reaction products formed in the pyrolytic cracking step to sep-` arate fractionated vapors boiling substantially in the range of gasoline, a-light reilux'condensate, and a heavier reflux condensate, subjecting the last mentioned fractionated vapors to treatment in the manner hereinbefore set forth, supplying 'said light reflux condensate to the catalytic cracking step and supplying said heavier reflux condensate to the pyrolytic cracking step.

Fig. 1 of the accompanying diagrammatic drawing illustrates in conventional side elevation one specific form of the apparatus to which the improvements set forth in this invention may be applied. Fig. 2 illustrates a modified form of re7 `actorirom that shown in Fig. 1. It is understood, of course, that the invention herein discracking andvisdirected to-aprocess in w i a pyrolytically formed gasoline is producedconcurrently with the production 4of-catalytically formed gasoline.

for the process, is introduced through line I containing valve 2 to pump 3. Pump 3 discharges through line 4' containing valve 5 into heating coil 6. Preferably also, the relatively light oil in line I is commingled withlight redux condensate separated in the manner to be described' and, as previously inferred, such light reflux condensate may in some cases comprise the sole charge to this step.' The oil in passing through heating coil 6 is vaporized and heated tc a cracking temperature by means of heat supplied from furnace l. The cracking temperature to which such oil is heated will in most cases fall within the range of 800 to 1200 F. and. usually within the range of 900 to 1050 F. Heated vapors leaving coil 6 vunder a pressure of from substantially atmospheric to 200 pounds per square inch or thereabouts pass through line B and may be 'introduced to either reactor B by way of valve '9 or to reactorI A by way of line lil containing valve il.

.The system illustrated in the accompanying drawing is shown as consisting of two reactors A and B in which catalytic cracking is accomplished and two communicating reactors A and B' in which eetruytic treatment of the pyrolytically formed gasoline and the catalytic converswitching the stream lof hydrocarbon reactants readily understood since the cracking 'reaction isv ordinarily accompanied with the deposition of carbonaceous substances which must lbe removed In the process illustrated in the accompanying drawing charging stock'may. comprise, for example, a relatively light readily' vaporizable hydrocarbon oil in which case such oil is introduced or supplied to the catalytic cracking step or in some cases the charging oil may comprise a relatively Y heavy dimcmuy veporizome hydrocarbon on and in such cases it is supplied to the pyrolytic cracking step. In still other cases the charge may I comprise a composite of relatively Jightand relatively heavyoils and in such cases it is usually desirable to supply this'oil to the pyrolytic crack- 1 `meister either diremmo the heating con but more generally to the fractionator receivingthe 'Y from the pyrolytic .vaporous reaction products cracking step.

Referring -now to the drawing, a relatively light readily vaporizable hydrocarbon oil, which in materials composited with one by period frequent regenerationv and thereby maintain the bed or beds of catalyst in a highly active state. In the process. of the invention herein described, it is 'intended that regeneration be accomplished by well known methods of which contain one or a plurality of beds of catalytic material through whichthe hydrocarbon reactants pass either in series or parallel.

Catalysts which have-been found to be elketive in Athe catalyticcracking of hydrocarbon vapors and in4 the treatment oi' pyrolytic'ally formed gasoline may comprise. for example, powder, pellets or granules'of synthetically prepared purified silica or other siliceous and refractory or morel of the compounds Iselected from the group consisting of alumina, zirconia, and thoria. In addition', the hydrosilicates of alumina, acid treated clays. or the like, have also been found to be eifective in the. cracking treatment of vhydrocu'bon `vapors. Although the catalysts above recited are generally considered to be the .preferred catalysts.

their use is not to be construed as alimiting. feature, for various other catalysts well known to those in the art may be employed within ,the

.some cases may comprise the sole charging stock '7l broadscope ofthe invention.

be'obtained when using the synthetically prepared catalyst, such as those of the silica-alumina or silica-alumina-zircon-ia type, but it is not intended that catalysts of the acid treated clay type be excluded from use in such process, for these catalysts will valso exert some benecial Conversion products leaving either reactor A or B are directed through respective lines l2 and i3 containing respective valves I4 and I5 and are commingled with a heated pyrolytically.

formed distillate supplied in the manner to be .described following Whichthe resulting mixture is intrduced to either one of the reactors A' or B depending, as in the above case, upon whether at such instance the reactor is employed in processing or the catalyst contained therein is undergoing regeneration. The invention contemplates switching streams of hydrocarbons introduced to reactors A' and B' at the same instant that the stream of reactants .is switched between reactors A and B.4 While catalytic conversion is being accomplished in reactor A the catalytic treatment is accomplished in reactor A and at the same time the/catalyst contained in reactors B -and B is undergoing regeneration. It follows as compared with those employed in reactors A and B, for whereas space velocities of the order of l.5 to 1 0. are employed in reactors A- and B, space velocities of the order of to 20 are employed in reactors A! and B'. Reaction temperatures within reactors A' and B' are preferablyv l of the order of 800 to 1200 F., but it is more reactor B' are directed through line Il containing valve I3 into line Il. In any event, conversion products in line i3 vare supplied to fractionator 2li. Fractionator 23 together with'the condensing and collecting equipment in communication therewith is preferably operated at a pressure of substantially the same order as that employed on the outlet of reactors A' and B'. Cbnversion products supplied to fractonator 2l are fractionated therein to separate fractionated vapors preferably comprising a full boiling range gasoline. such as, for. example. one having a 400 F; end point from in'suillciently converted hydrocarbons and the latter condensed within the' fractionator and removed as a liquid from the lower portion thereof in the manner to be described. I l

Fractionated vapors separated in fractonator 20 are conducted through line 2lv containing valve 22 to cooling and condensation in condenser 23. Distillate together with undissolved and uncondensed gases leaving condenser 23 is directed through line 24 containing valve 2,5 into receiver 26 wherein the distillate and gases are collected 'and separated. Undissolved and uncondensed gases collected and separated in receiver 26 are removed therefrom by way of line 21 .containing valve 278 and recovered as a product of the process. A portion of the distillate separated in receiver -26 may be returned to the upper portion of fractonator 20 by well known means, not shown, as a refiuxing and cooling medium in controlling the end point of the fractionated vapors and the residual portionthereof removed general practice to employ temperatures below 1000 F. The invention also contemplates sub- -stituting a single reactor for the double reactor,

such as A and A'. Fig. 2 illustrates this modi'ed form of reactor. In this figure appurtenances which are the same as those shown in Fig. 1 haya received the same legends. Thus, when processfing reactor AA', heated vapors in line 3 are directed through line Il) and valve ii into one end of the reactor .and pass in contact with a body of catalyst maintained therein. Conversion products are withdrawn from the opposite end of reactor-AA through line I6 andvalve I1 for further treatmentas will be described in connection with Fig. 1. Heated pyrolytically cracked distillate is introduced into reactor AA at an Aintermediate point and passes with the heated vapors -through the remaining portion of the reactor. Thus the pyrolytically formed distillate to be treated in the manner above described may be introduced to the singlereactor at some intermediatepoint so that the time in which these hydrocarbons remain in contact with the catalyst is not in excess of the time required to eiect the desired improvement in octanerating.

With reactors A and A' on process conversion products leaving reactor A' are directed through from receiver 26 by way of line 23 containing 'valve 30 and recovered as a product of the process or subjected to any desired further treatment.

Insufiiciently converted hydrocarbons separated in fractonator 20 vare directed through line v3l containing valve 32 yto pump 33 which discharges through line 34 containingvalve 35 into heating coil 36.. In some operations, also, heavy reflux condensate and/or a relatively heavyv oil contain-` ing diilicultly vaporizable hydrocarbons may be commingled with the insuilicintly converted hydrocarbons in line 34 in the manner to be described and the total mixture introduced -to heating .coil 36. The oil supplied to coil 36 in passing therethrough is heated to a crackingtemperature of the order 0f 850 to 1000 F., or thereabouts, by means of heat supplied from furnace 3l.v The heated oil leaving coil 36 is directed through line 38 containing valve 39 and intro-4 duced into reaction chamber 40 which is preferably operated under a superatmospheric pressure of the order of 100 to 500 pounds per square inch and wherein cracking instigated in the heating coil is allowed to proceed to a greater degree of completion.

Reaction products leaving chamber 40 are directed through line 4I containing valve 42 into vaporizing and separating chamber 43 which is Y preferably operated at a reduced pressure relative to that employed in chamber 40 and the pressure maintained therein will usually fall within the range of 50'to 200 pounds per square inch. Vaporous reaction products are separated from non-vaporous reaction products invchamber 43 line I6 containing valve i, and with reactors B and B' on process conversion products leaving and the latter substantially further vaporized to form a non-vaporous liquid residue which is recovered as a product of the process by way of line 44 containing valve 45. Vaporous reaction products together with vaporsv evolved within chamber 43 are directed through line 46 containing valve 41 into fractonator 48 and this fractionator may be operated at a pressure of Asubstantially the same order as that employed on the outlet of chamber 43. The vaporous reaction products are fractionated within fractionator 48 to separate the fractionated vapors from higher boiling hydrocarbons, containing in some instances only low boiling products, such as,for

example, hydrocarbons having 5 carbon atoms and less to the molecule. Generally, however, this fraction will include hydrocarbons boiling within the range of gasoline. The higher boiling hydrocarbons separated vin fractionator 48 are A condensed therein as reilux condensate and may at times be collected as a total reflux condensate while at other times further separation may be accomplished in fractionator 48 to separate a. light reiiux condensate from the heavier reflux condensate. Y

Fractionated vapors separated in fractionator 48 vare conducted through line 49 and may be directed through valve 50 to cooling and condensation in condenser 5I. VDistillate together with undissolved anduncondensed gases from condenser 5I is directed through line 54 containing valve to collection and separation in receiver 5B. Undissolved and luncondensed gases collected and separated in receiver 55 are removedtherefrom by way of line 51 containing valve 58 and recovered as a. product of the process.

In an operation involving the removal of only low yend point fractionated vapors from fractionator 48, such as hydrocarbons having 5 carbon atoms and less to the molecule, the distillate collectedin receiver 56 in such instance is removed therefrom by way of line 59 containing valve 60 and recovered as a product of the process. In an operation involving the removal of fractionated vapors from fractionator 48 over the full boiling range of gasoline, the distillate in excess of that required in refluxing and cooling the upper portion of -fractionator 48 is directed through line 6| containing valve |52 to pump 63. Pump 63 ischarges through line 64 containing valve 65 'i to heating coil 66. In `Qns latter type operation provisions are also made for by-passlng the cooling andcondensing step, in which case the fractionated A vapors in line 49 are conducted through line 52 containing valve 53 into line 64 by means of which they are supplied to coil 66.

Fractionated vapors supplied to coil 56, either as a liquid or vapor, are heated therein to a temverted hydrocarbons from fractionator 2l for treatment in the manner described. vLight rcflux condensate in suchv eases is conducted through line containing valve 8l to pump 82 which discharges through line 83 containing valve 84 into line 4 wherein such light reflux condensate commingles with the relatively light hydrocarbon oil and is subjected to conversion in commingled state therewith in the manner previously described.

A11 of the methods of operation described above ,relate to -a process in which the charging stock 4diflcultly vaporizable hydrocarbon oil or the composite charge is supplied through line 85 containing valve 86 topump 81. Pump 81 discharges through line 88 and the oil in line 88 may be directed through valve 89 into fractionator 4l wherein it undergoes fractionation in commingled state with the reaction products supplied -to fractionator 48 in the manner previously 'de'- scribed, or the hydrocarbon oil in line II may be directed through line 90 containing valve Il into line 16, commingling thereinv with reflux condensate in line 1li after which it is subjected to treatmentin the manner previously described.

Fromv the foregoing it is quite obvious that there are many-types of operation in which the improved form of this invention is useful, and it is my intention, therefore, not to limit the invention to any of the specific types of operation peratureof the order of 800 to 1100 F. by means of heat supplied from furnace 61. Heated vapors leaving coil 66 are directed through line 68 containing valve 68 into line 10 following which such heated vapors are directed either through valve 1| into line, I2. or valve 12 into line 'I3 for treat-l ment in the' manner previously described.

The total reflux condensate separated in frac- I tionator 48 is conducted through line 13 contain-- ing valve -14 to pump 15. Pump 15 discharges through lines 16 and 11 and valve 18 into line 83 by 4means of which such reflux condensate is supplied tc line- 4, commingling with the relatively light oil for treatment in the manner previouslydescribed. I p

In an operation involving both the separation fof light and heavy reflux condensate the two condensate fractions are separately removed from fractionator 48 and subjected to treatment in the manner to be described. Heavy reflux eenden-v sate in such cases is conducted through line 13A containing valve 14 to pump-.15 which discharges through line 'I6 containing valve 19 into line I4, "ommingliug therein with the insumciently conherein disclosed but rather to apply it generally 'to all types of operation in which a pyrolytically formed gasoline is produced kwhich may show improvements in octane rating' by catalytic treatment of the type herein described.

An example of one specific operation of the process as it may be accomplished in an apparatus such as illustrated and above described is approximately as follows: The chargingoi'l, a 33' A. P. I. gravity Mid-Continent gas oil, is heated to a temperature of about 950 F. 'Thejresulting heated vapors under a pressure of about 30 7 pounds per lsquaiefinch are passed in contact 'with a mass of silica-alumina catalyst of the type previously mentioned at a liquid hourly space veloeity of 4.

Conversion products leaving the mass of cracking catalyst are eommingled with a gasoline distillate separated in the manner to be described and the resulting mixture passed in contact. with a second,mass of cracking catalyst at a liquid hourly space velocity of 15. Conversion products leaving the last mentioned mass of cracking catalyst is fractionated to separate fractionated vapors of the gasolineboiling range from the higher boiling insuiiciently converted hydrocarbons and the former subjected to coolingY and condensation and recovered as a product of the process.

Insumciently rated in the manner described are eomniingicd converted hydrocarbons 1 sepa.-V

with a heavy reflux condensate the mixture subjected to. pyrolytic conversion in a. heating coil and communicating reaction chamber at a temperature of about 920 F. and a superatmospheric pressure of 200 pounds per squareinch at the outlet of said reaction chamber. ReactionI products leaving said reaction chamber are supplied to a vaporizing and separating chamber 'wherein Vaporous reaction products are substantially separated from non-Vaporous liquid residue andthe latter recovered as a product of the process.

Vaporous reaction products separated in the manner described are fractionated to separate fractionated vapors of about the gasoline boiling range,l light reflux condensate having an end boiling point not substantially in excess of 650" F., and heavy rei-lux condensate. 'Ihe heavy reflux condensate is supplied to the pyrolytic cracking step and the light reflux condensate to the catalytic cracking step. The fractionated vapors are separately` heated to a temperature of 950 F. and the heated vapors thereafter commingled with the conversion products from the first catalytic cracking zone and the resulting mixture supplied to a second catalytic cracking zone in the manner previously described.

From an operation employing conditions as above described one may obtain approximately 72% of 76 octane rating gasoline, approximately 11% of non-Vaporous liquid residue, the balance being principally carbon, gas, and loss.

We claim as our invention:

1. In a process for the conversion of hydrocarbon oil wherein relatively light readily vaporizable hydrocarbons are vaporized and heated to a cracking temperature and Asubjected to catalytic conversion in a zone containing catalyst capable of effecting the desired cracking reaction, and relatively heavy difc'ulty vaporizable hydrocarbons are subjected to pyrolytic cracking, insum-A ciently converted hydrocarbons from the catagasoline are supplied to the pyrolytic cracking step, the method which comprises commingling gasoline from the pyrolytic cracking step with the conversion products from the catalytic cracking step, and subjecting the resultant mixture to treatment in a catalyst zone separate from the catalytic cracking zone at a liquid hourly space velocity higher than that maintained in said catalytic cracking step to improve the octane rating of such gasoline. t

2. The improved process of claim 1 further characterized in that the gasoline supplied to the ciently converted hydrocarbons from the pyrolytic cracking step to the said catalytic cracking zone, heating fractionated vapors formed in the pyrolytic cracking step to a conversion' temperature, and commingling such heated vapors with the conversion products from said catalytic conversion step and subjecting the mixture to treatment in a catalyst zone separate from the catalytic cracking zone at a liquid hourly space velocity higher than that maintained in said catalytic cracking zone to improve the octane rating of the heated vapors.

4. A process for the conversion of hydrocarbon oil which comprises maintaining a catalytic cracking zone and a pyrolytic cracking zone, separately fractionating conversion products from both Y cracking zones toseparateiractionated vapors, including hydrocarbons boiling within the range of gasoline from higher boiling insufdciently converted hydrocarbons, supplying higher boiling insufficiently converted hydrocarbons from the catalytic cracking step to the pyrolytic cracking step, further separating the higher boiling insuilllytic cracking step, including those boiling above y ciently converted hydrocarbons from the pyrolytic cracking step into light and heavy reflux condensates, supplying said heavy reux condensate to the pyrolytic cracking step, supplying the light reflux condensate to the catalytic cracking step, heating the fractionated vapors from the pyrolytic cracking step, and commingling such heated vapors with the conversion products from said catalytic cracking step and subjecting the mixture to treatment in a catalyst zone separate from the catalytic cracking zone at a liquid hourly space. velocity higher than that maintained in said catalytic cracking zone to improve the octane rating of the heated vapors.

5. In a process for the conversion of hydrocarbon oil wherein relatively light readily vaporizable hydrocarbons are vaporized and heated to a cracking temperature andsubjected to catalytic conversion in a zone containing catalyst capable of effecting the desired cracking reaction, and relatively heavy diiculty vaporizable hydrocarbons are subjected to pyrolytic cracking. insuiliciently converted hydrocarbons from the catalytic cracking step, including those boiling above gasoline are supplied to the pyrolytic cracking step, the method which comprises introducing gasoline from the pyrolytic cracking step tothe catalytic cracking zone at some selected intermediate point S0 that Such gasoline DRSSES in 00nversion step; l

tact with the catalyst in said catalytic cracking zone at a relatively higher liquid hourlyspace velocity than the total reactants supplied to such zone. y

6.7A hydrocarbon conversion process which comprises pyrolytically cracking a relatively heavy 'oil to form thermally cracked gasoline, simultaneously subjecting a lighter oil to catalytic conversion in contact with a cracking catalyst, commingling at least a portion of said gasoline with the resultant catalytic conversion products, and subjecting the resultant mixture at conversion temperature to contact with cracking catalyst at a liquid hourly space velocity higher than that maintained in the first-mentioned catalytic con- 7. A conversion process which comprises catalytically cracking hydrocarbon oil, commingling thermally cracked gasoline with the resultant catalytic conversion products, and subjecting the resultant mixture at conversion temperature to contact with cracking catalyst at a liquid hourly space velocity higher than that maintained in the first-mentioned catalytic conversion step.

ROLAND B. DAY. ELMER R. KANHOFER.

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