US1788006A - Pressure still for cracking oils - Google Patents

Description

Jan. 6, 1931. D. A. YOUNG PRESSURE STILL FOR CRACKING OILS Filed July 15, 1927 2 Sheets-Sheet 1 pa MM 4. young Jan. 6, 1931. D. A; YOUNG 8,006

PRESSURE STILL FCR CRACKING OILS Filed July 15 1927 2 Sheets-Sheet 2 INVENTOR David A. young -20 the pressure still bymeans Patented Jan. 6, 1931 UNITED e was mm; A. YOUNG, or cnn's'rnn, DELAWARE, Assrenon 1T0 'smoLAm nnrmmecomrANY, on nEw YORK, n; "1., A CORPORATION OF'MAINE- rnnssunn s'rILL FOR cnAoxrNG one i Application med July 15, 1927. Ser-ia1No. 205,967.

In, the distillation of hydrocarbon oils under pressure, for :the production,bycracking, of lighter and lowerboilingioilsfrom heavier and higher boiling oils, it has become 5 common practice to prolong the period of operation by discharging, from the pressure still in which the operation is carried out, a part of the oil remainingunvaporizedin the still. One such particularly advantageous method of operation lsdescribed in Letters Patent No.,.1,598,136 issued to the Sinclair Refining- Company, August 31, 1926; another such particularly advantageous method of operation isdescribed in Letters Patent No. 1,634,666 issued to the SinclairBefining Company on an application filed April 8, 1924:, Serial No. 704,926. Hitherto, in such operations, it hasbeen customary to regulate the discharge of-unvaporizedoil from ranged in the discharge line externally of the still- I This invention relatesto an improved ar rangement of the regulating valve in the discharge line for carrying out this'typepf operation in pressure cracking stills. The m vention has several important-advantages; it improves the regularity'of operation of I such discharge lines and it alsoassists in keeping such discharge lines cleanover practically indefinite periods oftime. L Where the regulating valve is arranged in the discharge line externally of the still, particularly. where the discharge line extends into the still for any substantial distance, the discharge line tends to become'plugged or stopped, more or less frequently, between the regulating valve andthe inner end of the line opening into the still. lhe unvaporized oil in a pressure cracking still usually contains a fairly large proportion of pitchy or asphaltic constituents and frequentlycontains a substantialamount of suspended solid or semi-solid carbonaceous material. jWithi'n the confines of a relativelywsmall pipe, par; ticularly where the velocity islow, these constituents tend to form deposits which build up,plugging or stopping the line, Likewise, in some cases, cracking of the 011 may continue as it passes through the'disfchargelme of a valve ar andmay result in the formation of coky or carbonaceous deposlts 1n the line as a consequence.

According to the present invention, the

regulating valve'for controlling the discharge of unvaporized oil from the still'is arranged within the still and at'the extreme inner end. of thedischarge line. By this means, the reduction in pressure which takes place at this regulating valve in operation is madeefiective 'justas soon as the oil enters the discharge line" so that the increase in velocity due to'vaporization resulting from thisreduction in pressure is also made effective throughout the discharge line. This lncrease in velocity inhibits any tendency toward the formation of carbonaceous.depositsin the discharge line and, when made effective throughout the discharge line in ac'-' cordance with the present invention, keeps the discharge line clean throughout its length practically indefinitely. Further, in ac} cordance withthe present invention, the'operating extension for the regulating valve advantageously is "carried to the outside of the pressure still through the dischargeline, eliminating any necessity for astuifing box exposed to the pressure and temperature prevailing in the still proper.

The invention will be further described in ventionally apparatus embodying the inventime In the accompanying drawings v Fig. 1 represents, inelevationand partly in section and with parts broken away, a pressure still system embodying the inven-' tion, I

"Fig. 2 is a fragmentary elevation of a modified pressure still system,

Fig. 3"iS an enlarged fragmentary view showing a discharge line and regulating valvearranged in accordance with the invention, i

Fig. 4 is asimilarly enlarged view normal toFig.,3, I

Fig. '5 is a furtherenlarged detail of the regulating valve illustrated in Figs. 1 to A,

Fig. 6 is aview similar, to Fig; 5, showing 6 including a circulating pump 7 forcirculating oil from the bulk supply drum upwardly through the heatingritubes and back to the bulk supply drum. Vapors from the bulk supply drum 1 escape through vapor line 8to the reflux tower 9 located above the bulk'supply drum and vapors remaining on condensed escape from the reflux tower through vapor line ,10 to the condenser .11 arranged to discharge into the receiver 12. The distillate product is discharged from re 7 ceiver 12 through connection 13 and uncona run and for densed vapors and gasesthrough connection 14. The pressurein the system may be maintained and regulated bymeans of valve 15 in the vapor line between the reflux tower 9 and the condenser 11 or by means of. suitable valves arranged beyond'the' condenser ll'or' the receiver 12. Raw oil isintroducedinto theupper end of the reflux tower'9 through connection 16, and is preheat-ed as itfiows through the reflux tower 9 at the same time assisting in cooling and condensing the heavier part'of the vapors passing therethrough. Admixed raw oiland reflux-con densate flow back to the pressure still from the lower end of the reflux tower 9 through return line.17. A part of the cool raw oil is also supplied through connection 18 to assist' in cooling and lubricating the bearings of the circulating pump 7, being forced into the circulating still charge through the pump bearings. Discharge line 19 is provided'for the discharge, during operation, of "unvaporized pitch-laclen oil or, tar from the pressure still. Connection 20 is provided'for initially chargingthe still at the beginning of pumping out the stillat the end of a run.

In the modified pressure still system illus-l trated inFig. 2, a bed 21 of fullers earth, or similar absorbent material, is arranged in the bulk supply drum 1 on a screen 22 extending entirely across the bulk supply drum between the circulating connect-ions 4 to the battery of heating tubes and the circulating connection 6 from the battery of heating tubes. With this arrangement, the charge of oil circulating in the pressure still is caused to circulate and recirculate through the bed of fullers earth, or the like, as it circulates and recirculates through the heating tubes.

3 I Otherwise, the arrangement of this still sys tem is in general the same as that illustrated in Fig. 1. t I i V The present invention relates particularly sure still (the extension is designated 19a) and the regulating valve for controlling the discharge of unvaporized oil from the body of oil: inthestilldruhi is located within the drum mist the inner end of the extension 19a.11;Instead ofpassingdirectly through the wall of the drum 1, the operating extension for this valve passesto the outside of the still through the discharge line, as shown in Figs.

'The valve propeig'th'at is the closure means atthe inner end of the discharge line, may be" of several" diifering forms. The form illustrated in ig. 5'has been found particularly simple and eflective. As shown, it consists'of a conical plug 23 adapted to seat in the endof the discharge line extension 19a movable toward and away from" this seat by an operating extension 24 carried to the outsideof the pressure still-through the extension 19a" and through :a stufling box 25 ar ranged in the' discharge line externally of the still. "The operating extension 24 may or may not be keyed against rotation and adjustment of. itslyposition is provided by a threaded stem 26, to which it is connected, passing through a rotatable nut 27 The end of theiextension 19a forming a seat for the plu'g' 23 may be reinforced by a ring 28.

"The=closure means, in the form of valve illustrated in Fig. 6 and .7, consists of a plug 29, slidingwithinthe end of the discharge line extension 19a over a number of ports 30. This :p'lug may be guided by pins 31 moving in slots 32 in the extension 19a. The closure means, in the'form' of valve illustrated in F 1gs.'8'-and 9, consistsof a plug 33 sliding .within'the end of the discharge line extenof the' 'raw oil as well as on the character of'th'e products desired. For the production ofgasoline or gasoline-containing pressure distillate from gas oil, for example, pressures in the neighborhood 01'5100 to 300 pounds per square in'ch ma-y be used and the distillation maybe carried out at corresponding temperatures. After the still is brought to operating conditions of temperature and pressure, theintroduction of raw oil is begun and, in pressure still systems of the type illustrated, the introduction of raw oil into the upper end of the reflux tower may be regulated to condense and return to the pres sure still those components of the vapors heavier than desired as components of the distillate product. Likewise, either shortly after the still is brought to operating conditions of temperature and pressure or some time later,.the discharge of unvaporized oil through the discharge line 19 is begun. It will be understood thatthe lower end of the discharge line extension 19a is arranged somewhat below the normal liquid level in the drum of the pressure still. Where a bed of absorbent material is used,as in the apparatus illustrated in Fig. 2, the lower end of the discharge line extension 19a is advantageously arranged intermediate the liquid level in the still and the topof the bed.

Up to the time when the discharge otunvaporized oil through line 19 is begun, this line 19 is kept closed by means'of the valve at the inner end of the line within the still drum. The block-valve 37 is provided in the discharge line 19 simply for emergency use. When it is desired to begin the discharge of unvaporized oil, the valve at the inner end of the discharge line extension 19a is gradually opened until the desired rate of flow is established. Thereafter, the operation, it may be closed or partially closedor further opened as required to maintain or vary the rate of discharge of vunvaporized oil from the body of oil in the pressure still.

The reduction in pressure effected by the regulating valve at the inner end of the discharge line, in operation, results in a partial vaporization of lighter components of the discharged oil which in turn increases the volume of oil and consequently the velocity with which it flows through the discharge line, and, in the apparatus of the present invention this increase in velocity is effective throughout the discharge line, from its extreme inner end, to flow and preventing deposition which might tend to plug or stop the line.

Some of the advantages of the invention may be realized by arran ing the regulating valve on the inner end oi the discharge line within the still drum and carrying the operating extension of the valve to the outside of the still through a stuffing box arranged d1- rectly'in the still shell; but the arrangement more particularly described in connectlon with the accompanying drawings, with the operating extension of the valve carried to the outside of the still through the discharge line, is particularly advantageous.

In the apparatus illustrated, it will be noted that the discharge line extends into the drum downwardly from above the normal liquid level and opens downwardly into-the point during assist in maintaining body of oil in the still. This arrangement of the discharge line also assists in preventingstopping'or pluggingdue to deposition of carbonaceous solid or semi-solid material therein,v for example, as compared to a discharge line openinginto the bottom of the still drum or openlng upwardly intothe charge of oil therein. .The present invention is of special value and application in connection with pressure still systems in which the discharge line is so arranged as it provides for arrangement ofthe regulating valve inthe discharge line at the extreme inner end of the discharge line even though the discharge line extends inwardly into the still drum for a substantial distance.

Where the regulating valve has been arranged in the discharge line externally of the still drum, particularly where the discharge line has extended into the still drum for a substantial distance, the relatively slow velocity of the unvaporized oil passing through the discharge line before reaching the regulating valve has tended to cause stopping or plugging of the discharge line at a between the regulating valve and the interior of the still necessitating, when any such stopping or plugging occurred, premature shut down of the pressure still with consequent loss of time in useful production. This invention eliminates premature shut down of pressure cracking stills due to this cause.

I claim: 1. In a pressure carbon oils havlng a still for cracking hydrodrum adapted to contain a body of oil and a line for discharging unvaporized oil 'from such body extending a substantial distance into said drum, a valve'for, controlling the discharge of oil through said line located within said drum and at the inner end of said line having an operating extension to the outside of said drum passing through the wall of said drum withinsaid line.

'2. In a pressure still for cracking hydrocarbon oils the improvement comprising a drum adapted to contain a body of oil, a line ,for discharging 'unvaporized oil from such body, from a substantial and below the normal liquid level of the body of oil therein to a point external of the pressure still, means for maintaining super-atmospheric pressure on the pressure still including a valve for controlling the discharge of oil through said line, said valve being located within said drum and at the inner end of said line, and an operating extension from said valve to the outside of said druml In testimony whereof, I have subscribed my name.

DAVID A. YOUNG.

said line being arranged to extend distance within said drum

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