US1736325A - Oil still - Google Patents

Description

Patented Nov. I 1929 v UNITED srA CHARLES L. PARMELEE, orfonni'en, NEW JERSEY? on. i STILL" Application filed July '19,

My invention relates more particularly to that class of stillsinwhich the bulk :of'the oil being treated is maintained in a vaporizing chamber or tank in which the vapors or distillates separate from the liquid body. of oil and the temperature of the latter is maintained by circulating a stream'of oil therefrom through a heater and back into the main body of oil. My invention is more particularly designed for use in cracking oil, though it is also applicable in its broader aspect to straight distillation of oil. In processes of distillation, and particularly in pressure distillation where the object is to break down the hydrocarbons of the oil into lighter hydrocarbons, considerable amounts of heavy matter, carbon, tar, etc. are freed. If these heav ier materials are permitted to deposit in'the heating element, and particularly upon the Walls thereof Which are in contact with the heating gases or other heating medium, they tend to form a heavy coating thereon which insulates'the heating walls from the cooling effect of the circulating oil, with the result that the walls or portions thereof on which the deposition has taken place tend'to become overheated, and as the overheating increases the deposition and that "in turn' contributes to the further overheating, the tubes or other 7 heating elements are apt to be burnt and weak ened and sometimes burst unless the overheat ing is noted in time, and the stillshut downare restored. r V As cracking or OtlIBP-dIStIllfitIOII continues,

or the fire diminished until normal conditions the heavy matters tend to accumulate in the.

still system and as the oil is re-circulated, unless, as in my invention, provision is made against it, the heavy materials are again and again afforded opportunity to and do in fact deposit on the Walls of the heatingelement.

It is one of the purposes of thepresent invention to separate the heavymatter from the oil before the latter is returnedto the heating element whereby relatively clean oil only passes through the latter and hence the dep separate out by gravity from the body of oil while vaporization is taking place and return the thus purified oilto be again heated in the heating element, Other features'of the invention will appear hereinafter. V

r In the drawing '1' have disclosed preferred embodiments of my invention and have described the same inthe following 'specifica tion; itis to be understood, however, that the specific disclosure is for the purpose of exemplification only and that the'scope of the invention is defined inthe following claims, it being my intention to cover herein everything of patentable novelty in the disclosure. I

In the drawing, Fig. 1 is a diagrammatic view partly in section'and partly in elevation of a still construction embodying my inven tion, andFig. 2 is a fragmentary view show: ing a modification thereof.

In the form of the invention shown in Fig. 1, I have shown 3 a suitable furnace construc' tion comprising a fire-box 4, a'vertical throat 5, a heating flue. 6, and astack-flue 7 The heating flue '6 is provided with'bafiles 8 and 9, and a battery of tubes 10 extends vertically 7 therethrough'and is provided with upper and lower headers 11 and 12; At-13 I have shown in dotted lines a connection for returning a portion of the cooled products of combustion to flues l4underneath the fire-box and thence to the proximity of the burners 15 whereby'the' fresh hot products of combustion are somewhat diluted I by the cooler products, thus diminishing the temperature and increasing the Volume of the heating gases, avoiding s5 overheating of the front tubes in the first pass, and more evenlyand efliciently heating the tubes throughout. The specific construction of the furnace is, however, no part of the, present invention. 1

The bulkof the oil being treated is contained in a tank located a short distance away fromjthe furnace and is'heatedby circulating a stream ofoil therefrom through the heating element in the furnace and back to the tank.' The tank is shown at 17 in Fig. 1 of the drawings and is a relatively long cylindrical body entirely closed except for the connections hereinafter. described. 1 It is mounted'withits-axis vertical, the upper end 1 0 Fig. 1, so that the oil overflowing from the.

thereof extending well above the heating element in the furnace. The tank is divided by a vertical partition 18 which extends from the bottom thereof to a level substantially above the top of the heater thus dividing the lower portion of the tank into a receiving chamber 19 and an exhaust chamber 20. The receiving chamber is connected to the top manifold 21 of the top header 11 by a suitable return flow pipe 22. The exhaust chamber is connected to the manifold 23 of the lower header of the heating element by a circulating line which, as shown in Fig. 1 includes the horizontal pipe 24;, vertical gipe 25, pump 26, vertical pipe 2?,"and horizontal pipe 28. The pump, shown as of a double piston'rot'ary type, assists in rapidly circulating the oil through the battery of heating tubes10.: It not an essential elenent of the construction, however, and may i be dispensed with and thefpipe 24 directly conncctedto pipe 28 by a pipe asshown in Fig. 2. With the/construction just de scribed a stream of oil is continuously with- I lrawn fromth'e'chamber QO and flows through the pipe described to the heating element in the furnaceand thence through the upper return pipe 'to the receiving chamber 19. The thermalefiect in the heating element or battery of tubes is sufficient to produce the required circulation but I find that better results are obtained by employing the pump as the more rapid circulation produced is more efficient in keeping the heating tubes vswept clean of carbon deposit. It is to be understood that the efficiency of the heating element and the. rapidity of circulation are such as to maintain the oilin the tank l'f at the desired temperature whiclnin the use of the apparatus for cracking, is above the cracking temperature ofthe components of the oil treated vwhich are to be broken down. The tank and pipe connections may of course be heat insulated.

The volume of oil maintained in the system during normal operationis such as to.

Preferably, however, the level of oil the exhaust chamber 20 is considerably below that m recelvlng chamber 19, as shown in Latter to the former passes in a thin sheet down the partition 18, which is heated by the oil in the receiving chamber, a condition which is very favorable to the release ofthe gas and vapors. It will be noted that the connection of the return pipe 22 to chamber 19, is considerably below the level of the oil therein but more than half way from the bottom of the chamber. Theupward movement of oil in the chamber 19 is relativelysiow due to the relatively large cross section of the column of oil in said chamber as com pared to that of the stream entering it, thus affording a very favorable condition for the separation of any carbon and heavy tar formed in the passage of the oil through the heating tubes or through the pipe 22, and the portion of the chamber 19 below the connection of pipe 22 thereto otlcrs a quiescent zone in which the carbon and heavier tarry products separating from the circulating oil may settle out and deposit at the bottom. A, tar line 30 provided with a valve 31 extends substantially to the bottom of the chamber 19 and during the continuous operation of the still the heavier products of the crack operation including tar and carbon are continuously drawn oil. If desired, the tar line may be intermittently operated however. A manhole 32 is provided for cleaning out the chamber 19 when required.

The oilentering the chamber 19 is thus substantially freed of the heaviest portion of thejproducts of cracking and only relatively clean oil overflows into the exhaust chamber 20.' Thus, though in the apparatus described there is continuous recirculation of the oil through the heating element, the heaviest of the productsjformed are not returned to the latter so that the tendency to carbon deposition is minimized. A pipe 33 having a valve 84: is connected to the lowest point of the bottom ofthe tank for charging with oil in starting up. and pumping out when the operation is discontinued, and a valved branch 35 therefrom connects to a 'l' 36 between pipes 27 and 9.8 for withdrawing oil from these pipes between runs.

' The upper end of the tank 17 may constitute a vapor space only and it may be connected to the usual reflux tower, vapor line and condenser. Preferably, however, and as shown in Fig, 1 the upper end of the tank above the liquid receiving chambers 19, 20, is of sufficient volume and suitably equipped. to constitute a reflux, dispensing with a separate tower. In the construction shown in Fig. 1 the upper portion of the tank is provided with batl les 88 which may be of the type commonly employed in reflux towers, and the vapor line 39 leading to the condenser is connected directly to the upper end of the tank. The lowermost baflle is advantageously disposed to direct the flow of reflux into the exhaust chamber 20 where it minglcs only with relatively clean oil. By thus combining the refluxing space with the bulk supply tank of the still the construction is simplified and the tendency to carry drops or particles of liquid oil into the reflux tower and to puke due to the constricted passage between the shell containing the bulk of oil and the reflux tower as commonly designed, is obviated. The surfaces of the oil in both chambers 19 and 20. are free and in unobstructed connnunicatiou with the vaporizing and refluxing space to permit the ready release of vapors and gases formeda" The 'level of the liquid in the 'cham-' For continuousoperation a line '40 andspray head 41 are provided for the continuous introduction of feed oil to'maintain the desired volumewithin the still-which may or may not be supplemented by the introduction of oil through'pipes 33' and 35; Feed oil introducedthrough thespray head 41 passes to the exhaust chamber with the reflux and mingles only with the relatively clean oil therein. The Vapor line 39, condenser 42 and receiving drum .43 with its gas release line 44 and drawoff 45for distillate may be arranged and operatedias commonly employed in connection with cracking stills. A pressurerelease valve 46 inline 3.9 maybe employedfor controlling the pressure .in the still and reflux independently of the pressure in the condenser.

The apparatus claimed herein is illustrated and described in myl'copending application Serial No. 742,347, filed October 8, 1924, which has. matured as Patent: No. 1,613,718. The apparatus of' the invention is particularly adapted for the practice: of the. process claimed inthat patent;

Iclaimz ;.v w 7 1. In an apparatus of the class described, a

furnace, a conduit therein for passingoil to be heated therethrough, avaporizing chamber without the furnace, a compartment within said vaporizing-chamber, a second. compartment within said vaporizing chamber, connections including positive forcing means for conducting oil from said first named compartment once through said conduit" and thence to a point in said'second named com-- ing therefrom, acompartment in said vapor- "izing chamber to receive oil'from the heating conduit, another compartment in said vaporizing chamber'arranged to receive oil from theupperpart of the first named compartment, connections from both of said compartments to the heating conduit, and positive circulatingmeans in one of said connections arranged to transmitoil from the second named compartment once through the heating .conduitto a point inthe firstnamed cont.

partment a substantial distance above the bottom thereof. p

3. In apparatus of the class described, a furnace, a heating conduit for oil extending therethrough, a vaporizing chamber without the furnace, a compartment therein adapted to receive oil from the heating conduit, a sec- 0nd compartment within said vaporizing chamber adapted to supply oil to said heating conduit said compartments being arranged to permit unvaporized oil from the upper part of the first named compartment to be transferred to the second named compartment, con.-

nections from both of said compartments to the said heatingv conduit, and positive c1rculatmg means inone of said connections arranged'to convey oil from the secondnamed said compartment, means for withdrawing 9 settled tarry-matter from the lower part of the first said compartment, connections in cluding positive circulating means for circulating oil from the second named compare ment once through said heating conduit and back to a point in the first named compartment a substantial distance above the bottom thereof.

5. In apparatus of the class described, a furnace, aheating conduit extending therethrough, a vaporizing chamber without the furnace, a partition in the lower part of said vaporizing chamber dividing the chamber into two compartments said partition being imperforate below the point of introduction a of oil from the said heating, conduit and arranged to permit unvaporized oil to overflow from one compartment to the other within the vaporizing chamber, connections from the heating conduit to one of said compartments for leading oil thereto, and a connection from the other compartment to the heating conduit including positive circulatingmeans for leading oil from the latter compartment to the conduit said connections being arranged to permit oil from one compartment to be circulated once through the heating conduit to a pointin the other compartment a substantial distanceabove the bottom thereof.

6. In an oil still, a furnace, an oil heating conduit extending therethrough, a vaporizing chamber-without the furnace, a vertical partition in the lower'part of said vaporizing chamber dividing the chamber into two compar-tments said partitions being imperforate below the point of introduction of oil from said heating conduit and extending to a level above the upper level of the oil heating conduit in the furnace said partition being also arranged to permit oil from one compartment to overflow to the-other compartment within the vaporizing chamber,connections from the heating conduit to one of said compartments for leading oil thereto and connections from the other compartment to the heating conduit including positive forcing means for leading oil from the last named compartment to the conduit said connections being arranged to permit oil to be circulated from the last named compartment once through the heating conduit and back to a point in the other compartment a substantial distance above the bottom thereof.

7. In apparatus of the class described, a furnace, an oil heating conduit extending therethrough, a vaporizing chamber outside of the furnace, a vertical partition in the lower part of the vaporizing chamber dividing it into two compartments said partition being imperforate below the point of introduction of oil from said'heating conduit and extending above the upper level of the oil conduit in the furnace, a connection from the upper end of the conduit to one of the compartments at a point materially below the top of the partition and above the bottom of the compartment, and a connection from below the normal liquid level in the other compartment to the other end of the oil heating conduit, positive circulating means in one of said connections, said connections being arranged to permit unvaporized oil to be repeatedly circulated from the last named com partment once through the heating conduit and back to the other compartment.

8. In an oil still, a furnace, an oil heating conduit arranged in the furnace, a vaporizing chamber without the furnace, a vertical partition in the lower part thereof dividing the chamber into two compartments, said partition being imperforate and extending to a point above the upper level in the oil heating conduit in the furnace, a connection from one end of the heating conduit to a pointin one of the compartments intermediate the top and bottom of the partition, and a connection from the other end of the heating conduit to a point in the other compartment below the normal liquid level therein, positive circulating means in one of said connections, said connections being arranged to permit oil to be repeatedly circulated from the last named compartment once through the heating conduit and back to the other compartment.

9. In an'oil still, a furnace, an oil heating conduit arranged therein, an upright tank without the furnace extending from a point below the upper level of the heating conduit, a vertical partition in the tank extending from the bottom thereof to a point above the upper level of the heating conduit said partition being imperforate below the point of introduction of oil from said heating conduit and connections from opposite ends of the heating conduit to the compartments formed by said partition in the lower end of said tank and positive circulating means in one of said connections whereby oil may be circulated from one compartment once through the heating conduit to a point in the other compartment a substantial distance above the bottom thereof and over the partition in said vaporizing chamber.

10. In an oil cracking still, a furnace heating means within the furnace, a vaporizing chamber without the furnace comprising a receiving compartment and an exhaust compartment within the vaporizing chamber connections including positive means for circulating oil from the exhaust compartment oncethr-ough the heating means to a point in the receiving compartment a substantial dis tance above the bottom thereof, means for discharging oil from the upper part of the receiving,compartment into the exhaust com partment, and means for collecting the vapors from both compartments.

11. In an oil cracking still, a furnace, a heating means within the furnace, a vaporizing chamber without the furnace comprising a receiving compartment and an exhaust compartment within said vaporizing chamber, means for circulating oil from the exhaust compartment once through the heating means to a point in the receiving compartment a substantialdistance above the bottom thereof, means for discharging clarified oil from the upper part of the receiving compartment to the exhaust compartment, means for collecting the vapors from both compartments and for subjecting them to a refluxing operation, and means. for returning the reflux directly to the exhaust compartment.

12. In an oil cracking still, a furnace, a heating means within the furnace, a vaporizing chamber without the furnace comprising a receiving compartment and an exhaust compartment within the vaporizing chamber, means for circulating oil from the exhaust compartment once through the heating means to a point in the receiving compartment a substantial distance above the bottom thereof, means for withdrawing the tar and carbon from the receiving compartment, means for discharging clarified oil from the upper part of the receiving compartments to the exhaustcompartment, a reflux tower, and means for conducting vapors from both compartments therethrough, means for introducing fresh oil into the reflux tower, and means for conducting unvaporized fresh oil and re flux from the reflux tower directly to the exhaust compartment.

13. In an oil still, a furnace, a heating means within the furnace, an elongated tank loo - to permit overflow of oil between the separate compartments within the vaporizing chamber, connections including positive circulating means for leading oil from one of the compartments formed by said partition once through the heating means to a point in the other compartment a substantial distance above the bottom thereof, and a vapor line connected to the upper end of the tank.

14. In an oil still, a furnace, a heating means within the furnace, an'elongated tank arranged onia vertical axis and disposed without the furnace, a vertical partition dividing the lower end of thetank into two separate compartments said partition extending to below and being imperforate be low the point of introduction of oil from said heating means and arranged to permit oil to be transferred from the upper part of one compartment to the other compartment-within the vaporizingchamber, connections includ- .ing positive circulating means for leading oil from one of the compartments formed by said partition once through the heating means to the other compartment, a vapor line connected to the upper end of the tank and means for feeding fresh stock into the upper end of the tank. Y 7

15. In an oil still, a furnace, a heating means within the furnace, an elongatedv tank arranged on a vertical, axis and disposed without the furnace, a vertical partition dividing the lower end of the tank into two separate compartments said partition extending to below and being imperforate below the point of introduction of oil from said heating means, connections for leading oil from one of the compartments formed by said partition once through the heating means to the other compartment, means for discharging clarified oil from the upper part of th'elast named compartments to the other 7 compartment within the vaporizing chamber, a vapor line connected to'the upper end of the tank, and connections for introducing fresh oil into the vapor space in the upper end of the tank, and means for directing unvaporized fresh oil and reflux from the upper end of the tank directly to the compartment from which oil is withdrawn for recirculation through the heatin means.

16. In an oil still, a furnace, an exhaust chamber and a receiving chamber disposed without the furnace, a heatin conduit within the furnace, connections including positive means for circulating oil from the exhaust chamber once through the heating conduit to a point in the receiving chamber a substantial distance above the bottom thereof, overflow means for discharging oil from the upper part of the receiving chamber to the exhaust chamber said overflow means being arranged so that oil flowing from the receiving chamber to the exhaust chamber is heated by indirect heat transfer from oil in the receiving chamber.

1.7. In an oil still, a furnace, a heating conduit vertically arranged in the furnace, a vaporizing chamber without the furnace, a compartment within said vaporizing chamber, a connection from the conduit to a point in said compartment a substantialdistance above the bottom thereof, a second compartment in the said vaporizing chamber connected to the conduit and adapted to supply oil thereto, means for transferring unvaporized oil from the upper part of the first named compartment to the second named compartment and for positively circulating oil from the second named compartment once through the heating conduit to the first named compartment, and means for collecting the vapors from both said compartments.

18. In an oil still, a furnace, a heating conduit arranged therein, a vaporizing chamber without the furnace, a compartment in said vaporizing chamber, a connection from the heating conduit to a point in said compartment a substantial distance above the bottom thereof, another compartment in said vaporizing chamber arranged to receive oil from a point in the first named compartment above the normal liquid level in the second named compartment, connections including positive circulatingmeans between the second named compartment the heating conduit. and the first named compartment whereby oil may be circulated from the second named compartment once through the heating conduit to the second named compartment, and means for conducting away vapors from both compartments. I

19. In an oil still, a furnace, an oil heating conduit extending therethrough, a vaporizing chamber without the furnace, a compartment within said vaporizing chamber, a connection from said conduit to a point in said compartment a substantial distance above the bottom thereof, a second compartment within

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