US1752004A - Oil-cracking process - Google Patents

Description

MarchZS, 1930.v 1B. JAQUA OIL CRACKING PROCESS Filed Nov. 26,

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,4free/ver l Patented 'Mar'. 2,5,y 193Q `\E UNITED* sv'rATEs PATENT OFFICE JOHN B. JAQUA, OF ALHAMBRA, CALIFORNIA OIL-CRACKING PROCESS App/liaton l'ed November 26, 1926. Serial No. 150,762.

y Although my present invention is entitled, somewhat broadly, as referring to an oil cracking process, it should be understood that this invention relates more particularly to a process in which mineral oil is cracked mainly orentirely while in the liquid state or phase; and the mostk unique feature of my invention may be the technique by which impart'heat to crude or other oil, for crack-I 10 ing or analogous effect.

By the use of a novel process and apparatus which it is an object lof this invention to provide, I avoid or reduce to a minimum such local overheating of pipes, or the like, as tends to produce carbon deposits therein; I preferably adda non-aqueous heat-transferring fluid in increments, at successive stages of conversion, maintaining a temperature for a predetermined time and obviating the use of an unduly high initial temperature and I maintain in heating'and cracking coils a velocity of flow sufficient to carry forward such carbon as may inevitably result from the heating and/or cracking operations effected thereinw AsY pertinent to the main problems which it is an object of my invention to solve, I

quote the following from a work entitled Gasoline andAv Other Motor Fuels, by Ellis and Meigs (Van Nostrand Company, 1921, page 431) Many investigators have realized that overheating an oil has a tendency to decompose it into fixed gases and carbon. For example, by forcing oil through red hot pipes it is possible almost completely to break the oil up into fixed carbon and gas, without `the formation of any naptha, if the vapors remain long enough in contact with the heated surfaces. With direct firing. overheating,

is sometimes difficult to avoid. With this in view, many processes have been proposed for maintaining a mreuniform temperature byv means of fused baths of imetals or salts.

Although some of the results of my inventionimay be obtained by using fused baths of metals or salts, it is an object of my invention to `gain the essential advantages thereof, and additional advantages, by simoler and/or superior means; and, in preferred embodiments ofo my invention, using a comparatively stable oil (such as a thermolyzed gas oil obtainable as.bottoms) for a heat-transferring eect, and heating this medium to a temperature somewhat above that desired to effect an endothermic reaction of the raw mineral oil (such as a cracking reaction) I deliver the mentioned heat-transferring fluid, or its equivalent, in the form of separate small streams thereof, fed at successive points, into an advancing stream of the oil within which the mentioned reaction is to be produced i-the latter oil being prefermeans and methods permitting thermolyzed and relatively stable oil fractions to be repeatedly returned' and used as cycle stock) in such manner that they may not only serveA for a heat-transferring effect but may themselves gradually become decomposed into lighter products, and including also novel yfeatures of interconnection and organization of apparatus as herein described, may be best appreciated from the following description of illustrative embodiments of my invention, taken in connection with the ap- /Rpended claims and the ,accompanying draw- HSIs, in which- #The figure may be referred to as an entirely diagrammatic elevational view, with parts broken away, of an apparatus suitable for use in the practice of my invention.

Referringto the illustrated embodimentof my invention,'I show a cracking coil 11 as comprising a series of separate sections 11, 1lb, 11,J l1d and lle, this coil being preferably entirely unprovided with means for a direct heating thereof, and being shown as provided'w'ith a supply pipe 12, for the mineraly oil in which a cracking or other endothermic reaction is d'esired.-

Although it is an object of my inventiori) as indicated above, to obviate, so vfar as possible, the deposition of carbon or heavy residues Within cracking apparatus, in view of the factthat, generally speaking, oils may be'hrought near to their cracking temperatures Without such deposition, I may interpose in the supply pipe 12, or its equivalent, a preliminary or primary heater of any preferred type, such as that shown at 13 as comprising` a coil of pipe exposed to direct or indirect heating -15 by a flame 14,-oil being fed thereto by means such as a pump 15, assumed lto operateat a rate consistent with the opening of valves such as are indicated at 16 and 17 .l

After the oil is fed through the preliminary I heater 13 and therein heated, in the described anner or in an equivalent manner, to a temypeature slightly below that which may be pre-requisite toa cracking'or other desired physical or chemical effect, I prefer to add thereto the heat required -for obtaining such effect by introducing, as by Way of a manifold 18 and separately valved branch pipes 18a, 18b,'18c, 18I and 18e, a liquid heat-trans ferring medium, such as a relatively stable oil, heated to a .temperature slightly above' that required to effect th'evdesired physical and/or chemical change in the treated oil,x as the same is introduced through the supply j pipe `12 and` advanced through coil-11; and the mentioned stableoil, or its equivalent, may accordingly be brought-to the desired high temperature by 'means such'as a' so-called superheater or storage heater'19. shown as constructed similarly lto the mentioned preliminary or primary heater 13 and as heated by a flame 20,-a coil comprised in the mentioned superheater being shown as connected with the manifold 18 byrflvalved pipe 21.;

The cracking coil-11 being shown as provided with an. outlet 2 2, in which I prefer to interpose a pressure-reducing valve 23, said outlet may terminate, at an intermediate level, in a separator or in an interposed vaporizer 24,-t-his being shown as provided l with a vapor outlet 25,--through which mayVL pass such volatile products as are produced by the mentioned cracking reactionsvithin the coil 11; and thermolyzed residuum andffor heavy intermediate fractions may be Withdrayvn through aobottom outlet 26 and/ox" through an additional valved outlet, suoli as that shown'at 27 as connected with said'vaporizer' atl an intermediate level.

Although Il 'showbothof theI outlets 26 9 and 27 as connected withareturn pipe 28 'by which, uponrthe operation of a pump 29, a residue delivered through either of lsaid pipes ,-or a mixture of lsuch. residues, may bel 'ireturned through a pipe' 3() to the sup'erheater 55 19, Show saidputlet pipes' as also communi- -suchas a crude or toppedoil l(assumed to feet during its J j eating, by valved branches 31`and.32,iwvith a pipe 33,-shown as valved at 34 in a manner permitting the Withdrawal of said residue or any comparatively non-volatile product; but

I` prefer ordinarily to supplement the action of the so-called vaporizer 24 by the. use of an additional element, somewhat similar in construction connectiomsuch as separator 35. This is shown as connected, at an intermediate level, with the vapor pipe 25, and as provided With a pressure-reducing valve 36 in what I may term a final vapor outlet 37 for desired distillates. f

Assuming that the vaporizer 24 ami the separator 35 are to be operated at dill'erent` temperatures and pressures, aLnd in order to ,accomplishl both a condensing effect in these elements and an initial heating of raw oil to be-fed by the pump 15, or its equivalent, I may carry the raw oil pipe 12, or -its equivalent, through either or -both of the mentioned elements 24 and 35, as by providing coi-ls 38 and 39 therein (bubble plates being optionally interposed,` asat 40, in both or one of said elements) and I may also interpose in the vapor pipe 25,-or its equivalent, a pressure-reducing valve'41.

The separator 35, orits equivalent, being intended, when thus employed, to receive only such hydrocarbons as have passed 95 through the vapor pipe 25, I` need ordinarily make, in connection with saidI separator, no provision for the Withdrawal of such heavy residues as may be discharged from the vaporizer 24, past the valve 34 in pipe 33; but 100 I nevertheless shou7 the said separator as provided with a,bottom` outlet 42 (communicating both directly yand indirectly with the mentioned return pipe 28) and also with a .lateral outlet 43. The outlet 43 may deliver any desired intermediate fraction, by Way of :a valved pipe 34 (with which the mentioned pipe 33, from vaporizer 24 may be connected by tvalved lateral 44) into a tank not shown; and the outlet 42 is shown as provided With a valved branch 42- leading to a storage tank 45. The later is shown as connected by anoutlet pipe 46 (in which a pumpl 47 may be interposed) with the mentioned return pipe'28,-this arrangement adapting 115 said tank to serve for a make-up purpose hereinafter referred to.

In the ordinary use of an apparatus of the general character described, aV raw material contain littleor nothing of a gasoline frac-- tion) may be continuously admitted into the inlet end 12a of the pipe 12, or` its equivalent, receiving heat'and serving for a cooling ef-j passage through the coils 39 and 38, and being heated inthepreliminary or primary heater 13 to a temperature such as 700-800 F., Withoutany. appreciable cracking effect; the superheater or storage heater 19 may be maintained at a temperature 1 3.

(such as 90O"1000o F.) slightly above that required for a cracking or other endothermic action uponl the oil fed through the pipe 12,

or-its equivalent; and the valved inlets 18a-18e may be so spaced and adjusted as -to maintain throughout the cracking coil 11, notwithstanding an absorption of heat vltherein, a desired temperature gradient r `quantities as neither to occasion an excessive rise nor to permit an excessive drop in the temperature of the treated oil with which said re-circulated oil may be admixed. t For the purposes referred to, I may ordinarily use about three parts of, said re-circulated o'il A to one part of the treated oil.

not onl rI`he pipes employed in the .cracking coil 11, although perhaps ordinarily reaching a total length such as 50G-150() feet, are intend-y ed to havev a diameter (as, a diameterof 6, to 12") assuring continuous flow `therethrough; and ythe rate of said continuous flow may be such as to ',assure an advance of the resultant mixture at a rate such as one or two feet per second, or at a rate assuring a maintenance of the desired temperatu-re for a period such as 5-15 minutes, and obviatin deposition of caibom-about 200300 lbs. pressure being maintained The mixture of raw oil and re-circulated thermolyzed oil (or other liquid employed as a. medium for the transfer of heat) being preferably kept mainly or entirely in the liquid phase up to the time of its advance past the valve 23 or its entry into the vaporizer 24, an out-let pressure not exceeding about 50 pounds anda temperature such as 650 may e maintained in this element,-an outlet pressure not exceeding about 50 pounds, and a temperature between about 400`and 550o F., being then` appropriate to the separator 35. or its equivalent. I

It will be obvious that the foregoing 'temperatures are mere` approximations,the limits of variation tolerated being dependent upon the character of the raw oil treated ibut upon the specic product desired, and the described method being entirely suitable to use in the production of either gasoline, or kerosene, or lubricating oils and capable of use not only with heavy and/or intermediate oil fractions ofwidely different types but also capable of use with other re-circulated heatin mediums, such as molten salts or metals; ut my use of socalled thermolyzed oil or other'relatively stable oil or oil mixture as a heating medium has the important advantage that it not only favors production and separation of the desired products from the raw foil but incidentally augments the quantity of said products, by either a rapid or a gradual cracking of the heat-transferring medium itself,'-although the temperatures maintained respectively in the preliminary heater 13 and the superheater 19, as related to the cracking temperatures of the respective oils circulated therethrough, may be, under the conditions described, such as to result in only a very'slight or slow accumulation of carbon therein or in the cracking coil 11.

At the time operations are begun, an oil suitable for use as a heat-transferring medium may be advanced from any convenient source (as, for example, from the storage Y tank 45) to the superheater 19, simultaneously with the advance of raw oil, to be cracked, through the pipe 12; as soon as regular operation is under way, any desired proportion of the residual oils or bottoms which accumulate in the lower portionsof vaporizer 24 and/or separator 35 may be returned, by mentioned connections, through the pipe 28 and pump 29; and, in order to provide for eitheran automatic or a manual control of such return, and also for yarying the output of residuum or bottoms through the valved pipe 34 (which `may lead to a fuel oil storage tank, not shown) and through the valved pipe 42 (communicating with the tank 45) I show the bottom outlet 26 and intermediate outlet g 43 of the separator 35 as respectively pro- ,vided not only withmanual valves 48 and 48 but also with liquid-level-controlled automatic valves 50 and 51,--these latter being adapted, even though the valves 48 and 4X8 be kept Wide open, to maintain a predetermined level of oil in said vaporizer and in a part of said separator respectively.

In case exclusive reliance were to be placed upon the automatic valves 50 and 51, some of the mentioned pipes and/or valves might be dispensed with; but I consider it advantageous to provide all of the saine, in order to permit reliance upon the manual valves 48 and/or 49 to control bottom outlets; in order to predetermine'an upper limit of residuum or bottoms or intermediate fractions accumug lating in the vaporizer and/or the separator;

and in orderto facilitate such variations in through the cracking coil ywith (say) 3,000 vbarrels of a recirculated heavy intermediate oil mayy yield (say) 350 barrels of gasoline (via- 37) 500 barrels of a lubricant or other intermediate oil (via 34') and about 150 barrels of fuel oil via 34; but it should be understood that the recirculated oil may be of either higher or lower gravity and specific heat than the raW oil that is cracked by transbe disposed of (as fuel oil, or the like) orr used 'as a recirculated heat-transferring medium during a subsequent running of a quantity of less heat-reslstant oil.

By the describedmeans, some to 35%- of the raw oil initially containing no appreciable quantity of gasoline may be converted into ,a product marketable as gasoline,the conversion being presumably distributed bc- 'tweenthe successive sections of a Icracking coil of the general character described; but I call attention not only tothe high percent- Y age of gasoline and/or kerosene recovery and to the co/trollability, versatility and simplicity of the described apparatus andnietho'd but also to the fact that said apparatus and method are such as to permit operation for long periods (amounting to months, as against days or Weeks in the case of other t-ypesof apparatus currentl em lo ed) be- .'Y P Yn tween shut-downs for purposes of cleaning;-

out deposits of carbon, or the like.

Although I have herein described a single mfcompletembodiment of my invention, 4in;

cluding various optional features and sug-L gesting alternative connections and modes of operation, it should be understood not only (l) that I placeespecial emphasis upon my vuse of recircu-lated, relatively stable oil,`

added in successive increments and at a high temperature to a stream of, oil Nto be cracked thereby, and (2) that various features; of my invention may be capable of independent use, but also (3) that numerous modifications of both my apparatus and my yprocess might easily be devised, by those skilled in the artsi to which this case relates, Without involving the slightest departure from the spirit and scope of my invention, as the Asame is indicated above and in othe following claim but only in the limiting case Will a total uantity ofthe heat-transferrin oil be added-at lone time to the oil to be crac ed.

I clai'm as my invention:

sure, the `first-mentioned mineral oil mayfbe cracked; and advancing said medlum', -while so heated, into direct contact with" said firstmentioned mineral oil and thence, after a,` i

application of heat, subsequently to said contact, to said first-mentioned oil, for the desired cracking effect.

2. A method of cracking mineral oil which comprises: heating a fluent heat transferrlng medium in the form of a relatively stable oil to a temperature above the ,temperature at which, under the given conditions of pressure, the first-mentioned unineral oil maybe cracked; advancing said medium, While so heated, into direct contact with said mineral oil and, after a sufficient time to permit a cracking reaction: at the resultant temperature, into a region of relatively less pressure; and'taking off resultant vapors from said last-mentioned region,-the temperature of the relatively stable oil being such' as to obviate other application of heat, subsequently to said contact, to said first-mentionedI oil, forthe desired cracking effect.

3. A `method of cracking a mineral oil which comprises: yheating a iiuent heat-` transfer medium to a temperature above the temperature at which, under the given com ditions of pressure, the said mineral oil may be cracked; advancing said medium, ivh'ile so heated, into direct contact with saidmineral oil; advancing the mixture of-said medium and said oil in a stream, then separating re- Sultant vapors, and(l returning residues there- .y

by obtained for use, in like manner, as a heattransfer medium, in the cracking of an additional quantity of mineral oil.

4. A` method of cracking a mine-ral oil which comprises Lheating' a heat-transferring medium, in the form of a heavy oil, to a temperatureabove that at which, under the given conditions of pressure, the said lmineral oil may be cracked; vadvancing said medium iii separate increments and While so heated,into a stream of said mineral oil; and taking off resultant vapors. Y

f 5'. A method of cracking mineral bil which comprises: heatinga stream ofsaid mineral 011 and a stream of afluent,heat-transferring medium, inthe form of' a relatively stable 4oil, respectively Vto a temperature -belOW and to a\temp'erature above the cracking temperature of said mineral oil; and commmgling said streams during a continuedJ advance thereof. f

6. A nethod of cracking a 'mineraP oil l'. method ofcracking mineral oil which LWhich comprises-e heatinga stream of said mineral oil and a stream of a fluent heatcomprises: heating a iuent heat-transferring medium in the form of a relatively stable oil,

to a temperature above the temperaturel at which, under thegiven conditions of presb elow and to a temperature above the' crack-I ilo ing temperature of said mineral oil; and commingling said streams by adding said medium to said oil, during a continue advance thereof, in successive increments and at points spaced along said` mineral oil stream.

7. A method of elevating a mineral oil, largely liquid, to .a cracking temperature While minimizing the formation of undesired products tliereinqvhich comprises: bringing into direct contact therewith, during continued advance, a body of a stable oil Which contains sufficient heat to elevate said mineral oil to a cracking temperature,-the resultant admixture being advanced, mainly still in liquid phase and Without external application of heat thereto subsequently to the mentioned contact, toward a point of vaporization of lighter products at a less pressure.- Y

8. A method of elevating a mineral oil t kaiJ cracking temperature While minimizing the formation of undesired products therein yWhicheccomprises: bringing into direct contact therewith a body of a stable oil which contains sufficient heat to elevate said mineral oil to a cracking temperature by flowing onejof saidoils into a continuously advancing stream of the other of said oils, the heat in the relatively stable oil being suflicient, at the time of thel mentioned contact, to produce a cracking temperature in the mineral oil, Without subsequent, external Y applicationof heat.

9.J A method of elevating a Amineral oil to a cracking temperature While minimizing the formation of undesired products therein Which comprises: bringing into direct contact therewith a body of a stable oil which contains suliicient heat to elevate said mineral oil to a cracking temperature by flowing said stable oil into a stream' of said mineral oil in separate increments ad ed at successive points along the course o said stream, said increments being so spaced and so proportioned asto maintain a desired temperature in said stream for a predetermined time.

10. A method of imparting to an oil that heat which is required to effect a desired endothermic reaction therein Which comprises: heating another and more stable oil to a temperature above that prerequisite to the mentioned vendothermic reaction; and

thereafter directly admixing said oils, during continued advance in generally concurrent flow and Withoutrsubsequent application. of heat, in proportions predetermined with reference to the thermal requirements of-said reaction.

1l. A method of the general character defined inclaim l() in Which the second-mentioned oil is heated to a temperature but slightly -above the mentioned prerequisite temperature. l i

12. A process'of the general character defined in claimwflO in which the second-mentioned oil is an oil which is relatively insusceptible to the mentioned endothermic reaction.

, 13. A method of the general character defined in claim l0 in which the second-mentioned' oil is angoil of higher specific heat than the first mentioned oil.

14. A method of the general character defined in claim 10 in-Which the second-mentioned oil contains residual fractions obtained by the separation of a desired product from a mixture previously produced in the manner set forth in said claim.` i

15. A method of the general character delined in claim 10 in which the desired temperature is maintained, for a predetermined period, by making a series of small additions of said second-mentioned oil at successive points along the course of a stream of said first-mentioned Oil.

16. A process of the general character de-V fined in claim l0 in Which said oils are respectively heated, before they are .brought into contact, to temperatures respectively below and above the cracking temperature of said'first-mentioned oil, and in which a separation of desired products from a resultant mixture is effected by steps comprising a delivery ofthe same, at a diminished pressure, into a vaporizer. l

17. In means for the cracking of mineral oils: a superheater; a cracking coil comprising separate consecutive sections; means for delivering a liquid heat-transferring medium from said superheater, and in separate small streams, into said sections; means for forcing the oil to be cracked into a first of said sections; means for separating vapors from a resultant mixture; and means for repeatedly returning a heavy residue, through said superheater, to serve as said heat-transferring medium in said cracking coil.

18:'A method of cracking a mineral oil Which comprises: heating a stream of a heattransferring medium While out of contact with said mineral oil to a temperature above the temperature at which said mineral oil may be cracked; advancing said stream of heat-transferring medium While so heated into direct contact With a separately advancing stream of said mineral oil, to heat the latter during itsadvance and Without subsequent application of external heat; separating resultant vapors from the residue fractionating the vapors; and employing at least a portion of bottoms from the vapor fractionation as said heat-transferring medium.-

19. A method of cracking a mineral oil which comprises: heating a stream of a heat'- transferring medium While out of contact with said mineral oil to a temperature above the temperature at which said mineral oil may be cracked; advancing said stream of heat-transferring medium While so heated into direct contact with a separately advancing stream of said mineral oil, to heat the latter during its advance and without subsequent application of external heat; separating`resultant vapors from the'residue; fractionating the vapors; andC employing at least a portion of the resultant bottoms, together with atleast a portion of said residue, as said heattransferring medium. j

In testimon whereof, I have hereunto set my hand at os Angeles, California, this 15th day of November, 1926. f) u JOHN B. .JAQUA.

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