US1605063A - Apparatus for cracking oil - Google Patents

Description

Nov. 2 1926.

G, l.. PRlcHARD APPARATUS FOR CRACKING OIL vOriginal Filedflune 22, ,1915 2 sneets4s'nger1- nu ,0 Irma F \N\ NN IMWZUDZOU Nov. Z 1926. 4 1,605,063

G. L. PRlcHARD -APPARATUS FOR CRACKING OIL Original Filed June 22, 1915 2 sheets-Sheet 2 Iman/coc @LE-Mami fgt/W67@ Patented Nov. 2, 1926.

'NITED. STATES PTENT OFFICE.

GEORG PRICHARD, OF PORT'RTHUR, TEXAS, ASSIGNOR TO GULF REFINING CM- IPANY, F PITTpSnBUBG-H, PENNSYLVANIA A CORPORATION 0F TEXAS.

*APPARATUS ron Genome oIL.

Drignal application filed June 22, 1915, Serial No. 35,617. Divided and this application led November i 20, 1920, Serial No. 425,450. Renewed'September 18, 1926.

This invention relates to apparatus forl cracking oil and it comprises an advantageously vertical still body, agitating and scraping means therein, a shaft for operatlchamber; and it further comprises as a new apparatus a-still adapted to contain a body of oil, meansfor heating such' still to a high temperature, means for removing vapors therefrom, means for continuously feeding oil thereto, means for maintaining a pressure in the still, a stirrer mechanism adapted to keep granular carbon in suspension in the oil in the still, and to scrape the heated zone of the still, :such stirring mechanism includin@ a shaft adapted to receive power, journa ing Imeans on the still -for the reception of the shaft and fluid cooled cooling and sealing means inclosing suchjournal means; all as more fully hereinafter set forth and as claimed.

y When heavy petroleum oils, such. as gas oils, petroleum residua, etc. are heated to a high temperature say above 600 or 650 F., they break down with production of lighter oils, such as kerosene or gasoline; this being the Well known cracking process. tion is facilitated by operating under pressure. The elects of pressure upon the nature of the reactions are not well understood; it has apparently other actions than f that of merely raising the boiling point of the oil. Cracking has been performed in many types of apparatus but on a practical scale mainly in unobstructed stills externally L heated. lnv the cracking operation, aside from the formation of the lighter products stated, there is always a deposition of carbon and this carbon is in a hard, flinty form. lt deposits on the heated'portion of the still as a coherent, dense incrustation and not only is its deposition a source of grave inconvenience and expense, since it is hard to` remove from the heated portion of the still and causes that portion of the still to burnV through, but it also impedes the operation by impedng the supply of heat. l have found that it also exercises another action; that its presence has a marked influence upon the progress of 'the invention. rlFhis carment which is hotter than the body of oil,

The acbon has a catalytic influence in causing the deposition of more carbon, and it may easily be perceived from the fact that newly depositing carbonvinvariably forms onpreviously deposited carboni The carbon layer cohering to the heating element steadily' builds up, newly formed carbon cohering to that already in existence. The net result is a hard dense layer lcovering the heating element, and where this heating element is the bottom of the still the still bottom fills up and the plates areapt to buckle and warp.

ln the ordinary operation therefore, considering a body of oil under cracking distillation in a steel or iron still heated from the bottom, it will be seen that the oil in the bot"- tom layer is subjected to different inuences from that in the top layer inthat the oil in the bottom layer is not only subjected to more heat, since it is next the heating elebut it is in contact with carbonA which is exercising la catalytic effect. The top of the oil body, on the other hand, is cracking under a more uniform and lower heat and substantially in the absence of carbon. Carbon does not appear to form to any great extent save next the heating element, that is, next iron, or next previously formed carbon.

l have found that in cracking oils l can. produce very much more uniform results and at the same time attain considerable economies in operation by providing stirring mechanism in the lstill adapted to produce a constant dissemination of granular carbon or coke through the body of oil. ln so doing not only does the stirring keep the temperature of the oil body much more uniform but lt nd that the coke tends to form in small granules which do not adhere to thev heating elements to such an extent as is 95 usual. By keeping these coke granules separa-te and, as far as possible, uniformly distributed throughout the body of. oil, the newly formed carbon orcoke tends to deposit on that already in existence; that is, it deposits on the granules or forms new granules. rlhese granules being in every portion of the oil body, the cracking operation goes on much more uniformly and rapidly than is usually the case. Substantially li may say l am performing my cracking throughout the entire body of the oil, instead of, very largely, in the layers immediately in contact wlth the y heating elements. The stirring keeps all the .full of catalytically acting carbon.

oiluniform in temperature; i. e., the whole body of oil is at the high cracking temperature instead of, mainly, the layer of oil next the heating elements. And it is maintained With the opportunity for the deposition of the excess carbon formed by the presence of the catalytically acting coke granules, there is a greater tendency toward the production of saturated gasoline; something whichis highly desirable. p

It is however substantially impossible to luse a stirring mechanism of any kind in the ordinary type of stills and particularly when the still is run under pressure. 'Ihe walls of a still must be vapor-tight while at the same time the temperatures of oil distillation in the cracking operation are very high. It is ditlicult to furnish a tight gland or a journal for rotating power-driven elements of a stirrer which shall be both vapor-tight and uniform in engagement at all temperatures. As stated, .a cracking still is ordinarily run at temperatures in excess of (500 F. These difficulties are accentuated when the still is run under pressure; say, a pressure of 80 pounds to 300 pounds. p

I have however found that by a particular structure of the top of the still, I can maintain t'he portion of the still body carrying the journaling means and the journaling v means themselves at a lower and more convenient temperature than that prevailing in the body of the still. And with these means I can produce a j ournaling of the shaft which will be tight against liquid 'and vapor and which is not affected by the temperature of the still; in which the journalbearing has about the same engagement with'the shaft whatever the temperature of the still and of the liquid which the shaft-carriedmeans isr agitating. y

In the accompanyin illustration I have shown, more or less iagrammatically, an embodiment of mylinvention. In this structure Fig. 1 is a view, partly in elevation and partly in vertical section, of a still under this invention;

Fig. 2 is a detailed view on an enlarged scale ofthe still and stirring means; and Fig. 3 is a diagrammatical showing of a chain stirrer.

In this showing element 1 is va still of cy lindrical or other shape and made of any suitable material, .suchfas steel boiler plate. It may be provided with external or bottom firing means 2 of any suitable type. Art its top it is provided with vapor -outlet 3 leading to an air cooled chamber 4. Froml this chamber vapor line 5 passes to another air cooled chamber 6 beyond which is outlet 7 provided with loaded valve 8. Conduit 9 takes the vapors to diagrammatically shown a valve 11 which may be used to cause stillY pressure to prevail throughout the condenser. Conduit 12 leads into( release cham- 'ber 13 provided with gage glasses 14-and valved gas pipe 15. This gas release pipe may lead to any suitable means for utilizing the gas (not shown). Liquid is removed from this tank through valve draw-ofi' 16. The air cooled condensing chambers are provided with runback 417 connnunicating with both and leading back into the still.

The bottom 18 of the still may be, as shown, somewhat dished. Across the still4 at adistance from the bottom is an angle iron bracket 19 supporting a thrust collar, 20. rlhrough this thrust collar passes Vertical shaft 21 carrying cross bars 22 to which may be connected chains 23 (see Fig. 3) adapted to sweep the bottom orheated zone of the still. On the top of the still is .plate 24 forming the support for the cooled bearing. On this plate is mounted casing 25. Elements 24 and 25 may be a sin le casing. This casing is provided with in et 26 for cooling fluid and outlet 27. This outlet passes to cooling coil 28 inchamber 29 which may contain water or the like and thence to pump 30 which returns cooled fluid to the stated casingp/At its top this casing is provided with cover plate 31. As shown, this cover plate is secured in position by bolts and is gasketed to make it removable; but it may be riveted into place. Within the casing is bearin 32 through which the shaft passes. Meta licl packing 33 held yin place by element 34 .is provided forming a stung box.; rlhe coverv plate carries another bearing 35 also having a good packing around the shaft forming a secondY stun box spaced from the first stuliing box. t the bottom the still is provided with a draw-01E 37 for tar and granular coke. y Valve 38 mounted on rod 39 serves to control discharge of tar to the exit 40. rllhe valve rod passes through tubular casing 41 having a screw stung box 42 and is operated by lever 43. Motion is given the stirring mechanism by gears 44 from shaft 45. Cage 46 may be provided. 'Gutlet 47 (see Fig. 1) may be provided leading to a safety valve (not shown). rllhe still may be charged either continuously or from time to vtime through charging line 48. f

In the use of this structure, the still is charged to any desired height with the oil to be cracked or distilled, such as gas oil, pe-f troleum residuum, heavy crude oils, etc. Or a charge of ordinary crude may be placed in the still and distilled until the lighter oils are distilled. If the pressure of the still is not desired in the condenser, valve 8 may loe used and valve 11 left open; but if it is desired that the still pressure extend through while operating the stirrer. A,If desired, the` lpounds to bemost advantageous.

the condenser, valve 11 may be, closed to an appropriate degree and valve 8 kept open. In, either event heating is continued until gage 46 shows the desired amount of pressure within the still. During this heating the stirrer-is kept in steady movement over the heated zone, scraping the carbon from the heated zone as it develops. When carbon be ins to' develop, instead of baking on and ad ering to the heating'elements, it is removed and Aforms loose granular material which is kept circulating through the body of oil. When the desired amount of pressure is attained, valve 8 or 'valve 11 may be openedl to the desired extent and distillation under pressure begun. The pressure is kept at the desired oint byadjustment of the ring means an of the reducing valve used. While I may use from 80 to 300 pounds pressure, I have found a pressure of about 95 During this heating operation oil is kept flowing into the casing 25 through inlet 26 and is dis-y charged through outlet 27 This iow of oil keeps the whole bearing at a comparatively low temperature irrespectiveof the heat in the still. The influence of expansion being removed, a tight joint can be maintained oilmay be introduced through 26 at a pressure equivalent to that prevailing in the still.-

If the oil is the same character as that under distillation, it may be maintained at a somewhat higher' pressuregso as to make leakage inward. `Inany event, because of the doublebearing means 32 and 35, leakage is not to Y' be feared.

The stirrer may advantageously be keptV be kept at any temperature desired.

When the distillation has gone to the desired extent, lever 43 may be lifted, Withdrawing plug 38 and allowing the tar and v cokey c bon in the'still to go to exit through 37. The operation of this still may be conf tinuous, discontinuous and semi-continuous. Where it is desired to introduce oil throughout the distillation this may be done through the inlet 48, See Fig. 1

When the chain is ,used as is shown in Fig. 3 it should advantageously'be arranged to sweep the heated zone of the still and assist the stirrer in loosening any Yadhering carbon.

This application is a division of myprior wharrcnimis: a l l. An apparatus for treating oil under pressure comprising a still, a movable stirrer therein, an actuating shaft extending outside of the still, aehousingchamber surrounding` the shaft at its point of exit from the still, spaced stufling boxes on the shaft, one .such stufng box being `located. in the housing chamber and the other outsidelthereof, and

means for maintaining cooled fluid under l pressurel in the housing chamber and around the stuffing box located therein.

2. An apparatus for treating oil under pressure comprising a still, a movable stirrer.

therein, an actuating shaft extending outhousing chamber and the other being located outside thereof, and means l`for circulating cooled loil through the housingchamber and around the stufling box therein and for maintaining a fluid pressure in the housing chamber equal to or greater than that existing within the still. I

3. An apparatus for cracking oil compris- 4ing a still, heating means for a portion thereof, stirring means operating in proximity to the heated portion of the still to remove deposited carbon therefrom and to keep it in suspension in the oil in the still, a shaft for operating said stirring means, a stuffing box fdr said shaft, a chamber surrounding said stulling box, means for circulating oil through said chamber and around said stuffing box, and another stuiingbox for the shaft outside of said chamber, Vtogether with means for operating said shaft. i 4. In an oil still adapted 'to work under high pressure, a still body havingA a topro tary stirring-mechanism within the still, a

noA l shaft for operating said mechanism passing through said=top, a bearing for said shaft on saidc top, a, closed housing surrounding said bearing, a bearing for the housing through which the said lshaft extends, means for rotating the shaft, and means for .cir-

culating a cooling fluid through said hous ing and around the stufling box therein. A 5. In an`oil' still adaptedto Work under high pressure, a vertical casing, a stirring` device mounted to sweep the'bottom of the casing, a shaft f\or said device, a cross-bar and thrust collar holding said shaft at a point above the bottom, a top for the casing,`

4 ,fixedmy signature. j

application Serial No. 35,617, filed June 22,

GEORGE L. PRICHARD.

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