US1613735A - Process for cracking or converting oils - Google Patents

Description

Jan. 11 1927.

o. P. AMEND PROCESS FOR CRACKING OR CONVERTING OILS Filed March E5, 1922 y the same, whereby they are transformed or whereas such pressures are not practicable,

aan@ i... 11,1927. l 1,613,735

UNITED STATESl PATENT OFFICE.

OTTO P.- AMEND, 0F NEW YORK, N.

PaocEsskk Fon GBACKING on coNvEn'rme oILs. application aiea'xarciis, im. semi no. 540,725...

This inventionrelates to the art of crackvolving the external heating of oil in large ing crude petroleum, heavy naphthas, kerostills. The present process permits of the serie, and higher-boiling hydrocarbon dis'- employment, with safety, of a lpressure in tillates or residuals, orA combinations' of large stills'in excess of one hundred pounds,

converted into lower-boiling hydrocarbons, so vfar as -I am aware, vin any process insuitable for use in internal combustion en-. volving the heating of the oilexternally, and. gines, and for the various other purposes for more particularly, in large stills. l which low-boiling petroleum distillates are With a view to overcoming the disadvanemployed. The process is applicable either tages adverted to, various e'xpedients have 65 to hydrocarbons of the paraffin, naplithene, been suggested, such as tlie employment of or polymethylene series, or to mixtures of electric heating elements positioned within I hydrocarbons of the same or different series. the oil treating chamber, but these heaters The process is especially applicable to any have been of such structural character, and

- of the higher-boiling petroleum distillates, they were employed and operated under such 70 rsuch as kerosene, MexicanA distillates, gas conditions, that their useidid not produce oils. and fu'el oils. commercial results, and,-'so far asapplicant The cracking methods heretofore emhas been able to determine from authoritaployed commercially involve the external tive sources, the electrical expedieiits re- 2" heating of the oils, and the pronounced disferred to have been discarded as impractical. 75 advantages inherent in such heating are so Referring more 'specifically to the manner generally recognized in the art that a specific iii which the electricalheating elements were enumeration of such disadvantages'is not employed, attention is called to the facts that deemed necessary. It may be stated, howthey were heated to incandescence, a temever, that said processes are ineflicient, in perature entirely too high; that the'oils or 80 that they are slow in operation andv convert vapor under treatment were maintained at only comparatiyely small percentages of the comparatively low pressures, orfeven under oils operated-upon, and, moreover, are ata partial vacuum. conditions highly averse tendant with very considerable danger owto successful or etiicient cracking; and, fur'- 3 ing to the deposit or caking of heat insulatther, only a very small volume of oil, and 85 infr carbon on the bottom ofthe oil treating that generaly in a flowing condition, was still or receptacle. 4 operated upon, such as heating the oilwhile Moreover, the temperature required to flowing through pipes or tubes, a mode of properly crack the oils is so relatively high operation which has been demonstrated to 5 that when externally applied it results in be wholly impractical, because ofthe facts, 90

raising the temperature of the walls of the mainly, that if an efficient cracking temperastill to such extent that theirv capacity to ture is attained, the small volume of oil op- -Withstand the' pressure within the still is erated upon is a t to be over-cracked. i. e..l seriously impaired, and there is great danger partially gasifie whereas, if. a sufficiently 104 ofthe walls giving way under the pressure high temperature for the rapid cracking is 95 produced, so' that Anot infrequently, serious not attained, the flowing small body of oil explosions are thus occasioned. For these does not remain sufficiently long in contact reasons, amongotliers, great care must be with the heating'element to be effectively exercised in the carrying out. of the proccracked. v v

l5 esses involving external heating. The pi'esent invention overcomes the dis- 100 `The' process forming thesubject matter advantages inherent in the older, though still of the present invention enables me to segenerally employed, cracking methods recure any'l desired suitable cracking temperaferred to, ante, but has successfully solved tures. yetthe sides and bottom of the still the problem of cracking oils by utilizing ,5U or digester are maintained relatively cool, internal heaters, in the f orm of lelectric .re- 105 and, accordingly, the ability of the metal of sistors, under such conditions of operation the containing vessel to resist pressure is not that most unexpected scientific results are seriously impaired. J As 4a result, much obtained, as wel as exceptional commerical higher pressui'es may safely be availed of efficiency, moreA particularl as regards the "45 than can be safely used inthe processes inrapidity of cracking and t e large percent- 110 l as were not heretofore considered feasible.

Speaking generally, applicants process' embodies, in its substantial entirety, the

- following features: the employment of electric resistors,- preferably of carbon, submerged in the body of oil under treatment.;

the hea-ting of the resistors toa temperature' which will maintain Atheir exposed or active surface or surfaces at a temperature below incandescence, but sufficiently high to effect etcient cracking without causing undue gasilication, this temperature being dependent, of course., on the particular cracking temperature of the specific, material opera-ted upon; the treatment of a relatively large body of oil, in a comparatively quiescent condition, 1n contradistinction to treatlng, as

was heretofore the case when electric heaters were employed, a comparatively small body of oil, usually, as pointed out, in a iiowing state or condition; efficient retluxing of the uncracked oil, whereby the total yield of cracked products is greatly enchanced, and the employment of a relatively high pres-v sure, particularly'as compared w'ith the pressures suggested in the prior art process wherein it was attempted to use electric heaters. It will be understood. of course,

that the invention is not restricted to the employment, conjointly, of all the steps pointed out, since some of the operations, per se, are novel. In practice, I prefer to use an alternating current, though the process is not restricted to such current, and I have found that, with repect to the current,

the extent of cracking, assuming an eiiticient` cracking temperature is maintained, is dependent, mainly, on the quantity of electric energy efficiently vsupplied to the resistors. Good results have been obtained by using resistors in the form of slabs having a cross sectional area of 11/4, by (S1/g inches, and hav ing a length of 6 feet or more. It will be noted that the resistors employed are heavy or massive, and, accordingly, that the oil is exposed to extended carbon heating surfaces. The resistors accumulate more less carbon, i. e., are built `up by the deposit of carbon freed in the cracking process, so that they should be amply spaced apart from each other,and. also, from the walls of the still or treatingreceptacle in order to avoid short circuiting.

My. experience has demonstrated that in the employment ofsubmerged resistors, as

practiced'in the present process, acomparw tively high pressure is essential to effective commercial cracking. This seems to be occasioned by the fact that the resistors, at the temperature employed, appear to have somewhat of a tendency .to repel the oil and thus preclude intimate contact between the resistors and the oil. The result is that without employing a suitably high pressure, considerable ofthe oil is merely vaporized without being cracked. Accordingly, one of the mostl important functions of the pressure, in the present, process, is toA enforce close contact or engagement between the oil and resistors, though, of course, such pressure does incidentally, raise the boiling point of the oil. It is manifest, now that it has been pointed out, that the closer the contact is maintained between the oil and the resistors, the more effective will be the cracking, and vaporization without cracking will be reduced to a minimum.

For the reasons given, I prefer to operate at a. minimum pressureof from to 80 lbs., although intermediate pressures. from the minimum specified-to upwards` 0f 150 lbs. have all given excellent results.

as herein described, the temperature of the body of the oil can be regulatedfand contrplled to a nicety, and this nicety of temperature regulation results in much more regular production of a uniform quality of product than is possible in any process dependent on external heating. I prefer to operate at a telnperat-ure between about 800 F. and 1100o F.

Featuresof vthe process, other than those adverted to, will be apparent from the hereinafter description and claims, read in conjunction with the accompanying drawings.

The drawings illustrate, somewhat diagrammatic-ally, an apparatus forming part of my invention, which can be used in carrying out applicants process, although it will be understood that such apparatus is illustrative only of one type of apparatus which may be thus employed.

In the accompanying drawings,

F ig. l is an elevation, partly in section and partly broken away, of a still embodying the invention and adapted for carrying out the process of the invention, and

lfig. 2 is a fragmentary section online 2 2 ol Fig. 1.

vllclerring to the drawings, A is a still having an oil inlet a. and a gas inlet l cxtending nearly to the bottom of the still, the function of which will be hereinafter dc scribed. '.lhe still is heated by means of a submerged carbon heating element or yclements .(f, hereinafter termed a resistor, in the form of a plate, or tubular as shown, and, the said resistor isl provided with suitable tcrminals (l and d', properly insulated from the walls of the still. Moreover, tlnl resistor is spaced a very considerable distance from the walls of the still so as to pre- 'clude' any likelihood of short circuting.

Oil, which, if desired, may be preheated, is introduced into the still through the pipe ,a which is fed either directly from a pipe By the employment of the electric resistors lll) ' sistor its surface temperatureis raised to the desired degree for effective cracking,l

usually to approzrimately 800-v degrees F., which is considerably below incandesccnee. Naturally, however, the interior bodypof the carbon resistor is at a somewhat high'- cr temperaturev than the teniperature of its surface. The volatile products of the cracking processI pass off from the still, and enter a reliuxtower A. superimposed on the still, whence they enter an outlet pipe B. Tower A is preferably of such height and size that during the passage of the products' of the cracking operation therethrough sufficient refluXingvact-ion will-take place so as to allow the return to the still ofuncracked oil vapors carried along by the products of the cracking operation, andl through such refluxing action enhance the quality and quantity of the resulting product.

A further refluxing action may be carried on by inclining the outlet pipe B in an npward direction, althouglnif desired, the pipe B may extend in any desired direction if the tower A is sufficiently high to properly carry out its functions.

Pipe B leads to a cooling coil D, housed in a casing E, through Which a cooling medium, such as Water, is circulated through inlet and outlet pipes e and e", respectively.

During the passage of products of the cracking operation through coil D, the temperature is sufficiently lowered to condense the greater portion thereof, although a small percentage of such products remain 4in gaseous forma` The condensate from coil B, passesthrough a pipe F, controlled by a valve 1"', into a receiving tank (l. rlhe liquid is retained in tank G, but any gaseous or uncondensedI volatile products finds exit through a pipe l1., provided with a relief valve Il', whence it passes into a gas ta-nk Il. 'lank ll, is provided with an outlet pipe i, in which is located a manually controlled valve z", whereby the gas may be fed "to a burner I, for the purpose, if desired,

of preliniinarily heating the oilv prior to its introduction into the still. The still is provided with means, such as a valved draw-off pipe l', whereby separated carbon or oil residues maybe removed therefrom. The

tank of the reservoir G has a draw-off pipe 0, controlled by a valve g2, through which vthe condensate may be drawn-olf, and furusually considered advisable to remove air v from the apparatus, and this may be done by displacement by causing a flow of suit able gas, such as natural gas, therethrough, which gas is introduced into. the still through pipe b. Still A is thereupon supplied with oil, either intermittently or continuously, preferably in one of the Ways specified, and I have found itadvisable to fill the still to about two thirds of its capacity, the resistor c beine preferably completely submerged therein.- Electric current is then supplied to the' resistor, whereupon, in a short time, an autogenous pressure is ybuilt up in the still, preferably ranging from 75 to 150 pounds, and which may be regulated'by means of the pressure valve B or in any other suitable Way. The desired cracking temperature, dependent to some extent, of course, on the most effective cracking temperature of the particular oil under treatment, is constantly maintained,

free 'from uncracked oils and other undesirable products. In fact, it may be much more readily purified 4than the cracked oils heretofore pbrodueed by other commercial processes. rovision 'is made I'for such a thorough reflux action. as to practically preclude all uncracked vapors from entering the condensing coil d, thereby materially increasing the effectiveness of the process.

In practice, it is found that even whenV the oil is subjected to the highest temperatures required, the walls of the still remain relatively cool, and, accordingly, the danger of exploding the still is entirely avoided. I am thus enabled to employ much higher temperatures, as Well as much greater pressures, than could possibly be availed of in an externally heated still, and with practically no attendant danger. Accordingly, the efficiency of the process is very materially higher than those processes dependent on .external heating. As a further re sult, I am able to successfully crack oils, such as kerosene, having a range of boiling points above 130 degrees C. and below 260 degrees C. None of the processes' in commercial use can be utilized for cracking kerosene successfully since their commercial operation is restricted to hydrocarbons lhav- C. rllhis fact emphasizes the pronounced diference in a licants lrecess and its inherent advantages over the processes now in use. Moreover, the durability of the still is greately enhanced for the reasons adverted to.

Applicant has observed that7 when cracking oils in externally heated stills, carbide of iron is produced to a material extent, which carbide reacts on thel oil, under the conditions of operation, to produce aromatic hydrocarbons, an undesirable result. rlhis result is obviated by applicants process.

lt will be understood that while app-licants vprocess has beendescribed sin its entirety, the invention is not limited to all the operations 'set forth, but is as broadly novel as is commensurate with the appended claims.-

Having thus fully described the invention, what l claim as new and desire to secure by Letters Patent is:

l. 'l`he process ot converting heavy hydrocarbons into lighter hydrocarbons which consists in heating a relatively large body of such heavy hydrocarbons to a suitable cracking temperature, but considerably below the incandescent temperature of carbon, by a plurality of electric resistors of massive construction submerged in the oil and while maintaining the oil at a minimum autogenous pressure of 75 pounds.

2. 'll`he process of converting hea-Vy hydroystruction submerged in the oil and while maintaining the pressure in the still in eX- cess of 75 pounds.

3. The process of converting heavy hydrocarbons into lighter hydrocarbons which consists in heating a relatively large `body of such hydrocarbons to a temperature considerably below the incandescent temperature of carbon, ina still 4or receptacle of the general type used for cracking, by a plurality of electric resistors of massive construction submerged in the. oil, and suiliciently spaced from the walls ot the still to preclude short circuiting and maintaining a pressure in the still in excess of 100 pounds.

4. The process of converting heavy hydrocarbons into lighter hydrocarbons which comprises immersing in a relatively large body of said heavy hydrocarbons a. plurality of electrical resistors of massive construction and heating the saidhydrocarbons by means of such resistors to the cracking temperature and pressure.

ln testimony whereof l have signed the foregoing specieation.

@TTG l?. AMEND.

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