Патент USA US2133240код для вставки
Oct. 11, 1938. 2,133,240 H. v. A'rwr-:LL TREATMENT OF' HYDROCARBON OILS Filedpec. 31, 1957 WN INVENTOR H4/?0¿D K 4TH/[LL Ik BY H' S ATTO RNEY Patented oct. 11, 193s 2,133,249î UNITED STATES; PATENT OFFICE ¿ 2,133,240 TREATMENT 0F HYDROCARBON GILS Harold V. Atwell, White Plains, N. Y., assigner to Process Management Company, Inc., New York, N. Y., a corporation of Delaware Application December 31, 1937„ Serial No. 182,678 ` 4 Claims. This invention relates to the cracking of hydrocarbon oils for the production of lower boiiing products such as gasoline. In accordance with the invention, hydrocarbon which it is desired to subject to cracking, is treated with a solvent capable of removing as phaltic materials that may be contained in the oil, the oil from which the asphaltic material is removed is subjected to a cracking operation 10' and the asphaltic material is injected into` the oil undergoing cracking so as to thus subject the asphaltic material to cracking for conver sion into lower boiling products. The invention is especially directed to the 15 processing of stocks containing residual con stituents of crude petroleum, such as topped and reduced crudes. Such stocks contain greater or less proportions ci asphaltic constituents whichy are very readily converted into coke when the cil is subjected to cracking. By removing these potential coke-forming constituents from the ¥ oil, the oil is made susceptible to cracking under much more drastic conditions, characterized withv greatly increased rates of cracking perv pass with eut coking diiiiculties. In accordance with the invention these asphaltic materials which have been removed from the char-ging stock are in jected into the stream of oil undergoing cracking so as to thus advantageously accomplish. the 30 cracking of the asphaltic materials and effect conversion into additional gasoline. constituents. In practicing the invention the charging stock is treated with a liquefied normally gaseous hy drocarbon, such as ethane, ethylene, propane, propylene, butane, butylene, or mixtures thereof.,` under conditions in which such hydrocarbon acts as an anti-solvent of the asphaltic constituents which are precipitated from the oil. The oil thus freed of the asphaltic, coke-forming con 40 stituents, may be subjected to cracking at a high rate of cracking per pass adapted to sustain a conversion into high anti-knock constituents and the precipitated asphaltic material is intro duced into the cracked products so that the = asphaltic material is raised to a cracking tem perature and subjected to conversion. In this way the de-asphalted stock may be subjected to temperatures and longer times of re action than are applied to the precipitated rma terial which may be introduced into the crack zone at the latter portion thereof so that the precipitated material may thus be subjected to cracking for a’shorter time than the de asphalted oil. Although various solvents, or anti-solventsl of (Cl‘. 1796-50) asphaltic material, may be employed in the practice of the invention, the hydrocarbons men tioned are well adapted for the purpose of the invention because of their excellent anti-solvent properties, at temperatures close to normal tem peratures, with respect to asphaltic constituents contained »Y in petroleum oils. Propane or va hydrocarbon gas consisting essentially of pro~ pane, is recommended because of its ready availability. . > In order to more fully disclose the invention, reference will be had- to »the accompanying drawing, which is a flow diagram illustrating a particular embodiment of the invention. ' In the drawing II! represents the oil stock tank 1.5¢î containing the oil which it is desired to treat, and H indicates a suitable source of liqueñed pro pane maintained under appropriate pressure.. The oil is drawn by the pump I2 and passedthrough charging line I3 into a. mixer I 4 and the> propane is drawn by pump I5 and passed through charging line I6 into the mixer I4. The charg to a heating coil IT and connected to a heating stock and the propane, 25 ing line I3 is connected the charging line I6 is coil` I8 so that the oil either or both, may be desired temperature in heated to maintain the the mixer I4 and in a settling tank I9 into which the mixer discharges.v The heating coils I1 and I8 may be heated in any appropriate manner, as by heat exchange 30 with products from the cracking operation, and the mixer I4 and settling tank. I9 are preferably insulated to retain heat and facilitate the ac curate control of the temperature in the mixer and settling tank. By reason of the contacting of the oil and the 35 Solvent in the mixer and settling tank, asphaltic constituents are precipitated out of the oil solu tion and there is collected in the tank i9 a super~ natent oil layer and a bottom layer of asphaltic material. The oil thus- freed of asphaltic ma» terials flows into the cracking stock tank 20- andA the asphaltic material is drawn into the asphalt tank 2|. While the asphaltic material exists as potential solid material, it is removed as a liquid 45 by reason of the fact that it is» in solution with a certainv amount of the liquid propane and is with» drawn to the asphalt tank. For purposes of sim plicity, a single settling tank I9 is shown but it is to be understood that it is often desirable to 50 employ a plurality of settling tanks to facilitate a ' better separation between the oil and the as phaltic material. The de-asphalted cracking stock collecting in the tank 20„ may, if desired, be freed of pro-- 55 . 2,133,240 2 pane by reduction in pressure and the flashed propane cycled to the propane tank H for re use, or the cracking stock containing the propane in solution may be passed directly to the cracking zone. As illustrated, the pump 22 withdraws the de-asphalted cracking stock from the tank 20 and directs it to a cracking coil 23, positioned in a furnace 24 adapted for supplying heat adequate for cracking. The coil 23 discharges into a 10 ~secondary cracking coil 25 positioned in a heat ing or heat-retaining chamber 26 and a pump of, for example, about 140° F. to 180° F. In prac ticing the invention under somewhat less selec tive conditions, while the oil may be substantially freed of asphaltic constituents, there may be cer tain proportions of oil constituents contained in the solvent-asphalt mixture which will lower the melting point.' The asphaltic material as re moved from the oil by the action of the propane and collected in the tank 2|, will be in liquid form by reason of the presence of the liquid pro pane (ordinarily about 50% of propane by vol and sometimes due also to the presence of 21 withdraws asphaltic material from the tank . ume), certain amount of oil constituents. The liquid 2| and introduces this material through line 2B asolution of asphaltic material may be readily in into the secondary cracking coil 25. The cham jected into the stream of cracked products to l5 ber 26 may be supplied with furnace gases from 15 thereby accomplish the cracking of the as the furnace 24 or otherwise heated under condi phaltic, coke-forming constituents in an advan tions of relatively low heat density. In lieu of tageous way. arranging the chamber 26 as an element sepa The selective action of propane as a precipi rate from the furnace 24 the heating coil 25 may tating solvent for asphaltic material contained 20 be disposed in the furnace 24 in a Zone of rela in hydrocarbon oil is exhibited at temperatures tively low heat density therein. If desired, the of about 70° F. to about 150° F. An advantageous asphaltic material being introduced into the coil temperature is 100° F. to 140° F. with volumes of 25 by the pump 21 may be preheated before be ing admitted to the cracking coil, as by means of liquid propane of about three to ten to one vol ume of oil. Under these conditions the action 25 a heating coil,29. In practicing the invention, of the solvent is highly selective in precipitating the oil in the coil 23 is subjected to high cracking asphalt with a minimum removal of oil. As the temperatures under conditions of high cracking temperature is raised increased proportions of per pass and the stream of cracked products flowing to the coil 25 is utilized in accomplishing oil will be contained in the solvent-asphalt mix 30 ture. 30 the cracking of the asphaltic material introduced With ratios of propane to oil of as low as three into the cracking coil 25. to four to one at a temperature of 120° F. sub The combined cracked products from the stantially all of the asphaltic material may be ' cracking coil 25 pass through transfer line 30 precipitated out from the oil. The de-asphalting into a separator or vaporizer 3l wherein separa is carried on under pressures appropriate for 35 35 tion of vapors from residue takes place. The sep maintaining the solvent in liquid form under the arated vapors are fractionated in fractionator 32 to separate as reflux condensate insuñìciently temperatures used and may well be carried on under pressures of about 250 to 400 pounds. converted constituents from vapors which are condensed in condenser coil 33 and collected in receiver 34 as a desired product. Reñux conden sate collected in tower 32 is advantageously sub jected to further cracking either by being cycled to the cracking coil 23 or by being directed to a separate cracking zone. In a preferred embodi ment of the invention, the vapors in the tower 32 are subjected to a primary fractionation to separate out a relatively small quantity of pri mary reflux condensate which is collected at the bottom of the tower 32 and a much larger pro ; portion of secondary reflux condensate collected on a trap-out tray 35. This operation is advan tageous in removing from the vapors certain polymer products of cracking including certain tarry or asphaltic products of reaction and the >heavy reflux condensate containing these mate rials is advantageously cycled by a pump 35 to the oil stock tank I0 so that it may be admixed with the charging stock for treatment with the solvent. The secondary reflux condensate may be cycled by a pump 37 to the cracking coil 23 or it may be passed to a separate cracking unit not shown. The term “asphaltic material” as used herein refers to certain black, pitchy material existing ' in the oil as a potential solid or semi-solid. The term is intended to apply to constituents having a melting point of about 80° F. or higher. Or dinarily in the treatment of crude petroleum re siduum in accordance with the invention the asphalt precipitated out, upon removal of the solvent, will have a melting point of about 140° F. to 180° F. In accordance with the invention the solvent may be applied in a highly selective manner to separate out an asphalt, which upon removal of the solvent. may have a melting point The solvent treatment may be employed to re move from the oil, in addition to asphaltic con 40 stituents, certain resinous constituents. By re moving the resins, as well as the asphaltic mate rial, the treated oil is further improved as a cracking stock with respect to coke-forming pro clivities. '_I‘he resinous fraction may be removed together with the asphaltic material, or if de sired, the oil may ñrst be treated with the solvent to remove asphalt and then further treated with the solvent to remove the resins. In the two stage operation it is preferable to use a slightly 50 higher temperature for the resin-removing op eration, thus for example with ratios of propane to oil of 4-6z1 and with temperatures of about 13G-135° F. for the de-asphalting stage; tem peratures of about 150°-1'75° F. may be used in 55 the de-resinifying operation. Both the asphal tic and resinous fractions may be conducted to the reaction coil 25 so that these materials may be converted into lower boiling products. The de-asphalted stock, either with or without 60 the removal of solvent, is passed to the cracking coil 23 and subjected t'o relatively drastic crack ing conditions therein to effect conversion into gasoline constituents of superior anti-knock quality. By way of example, it may be stated that 65 the deasphalted stock may be subjected to crack ing temperatures of 900° F. to 1000° F. with a time of reaction in the coil 23 adequate to effect a conversion per pass (as measured by conversion into 400° F. endpoint gasoline) of 20% to 30%. 70 The asphaltic material, and the resinous mate rial and certain heavy oil constituents that may be included with it, preferably after having been preheated to temperatures, such as 600° F. to 800° F., is injected into the stream of cracked 75 2,133,240 products discharging from the cracking coil 23 to thus raise the asphaltic material to a high Vcracking temperature, such as about 900° F., and effect the cracking of the asphaltic constituents. In this way the asphaltic constituents may be subjected to a high rate of conversion tending to the formation of gasoline constituents of su perior anti-knock quality. The cracking opera tion in the coils 23 and 25 is carried on under superatmospheric pressure, such for example as 400 to 800 pounds, and the pressure on the cracked products is preferably reduced in the evaporator 3| to facilitate the distillation of cracked products. Appropriate reñuxing is carried on in the tower 32 to form a relatively small quantity of high boiling reflux condensate which may contain certain asphaltic or tarry products of reaction and this heavy reflux condensate is advantageously cycled to the oil stock tank I0. The lighter re 20 flux condensate collected on the trap-out tray 35 is subjected to further cracking as by being cycled to the cracking coil 23 and the desired gasoline product is collected in the receiver 34. The ñXed gases from the receiver 34 or the 25 fixed gases obtained in rectifying the product collected in 34, may advantageously be cycled to the solvent storage tank Il to be mixed with the solvent therein. In the operation in which the de asphalted cracking stock passing to the tank 20 30 is not freed of its ñxed gas content, the fixed gases contained in the oil passing to the cracking coils 23 and 25 will undergo reversion reactions therein so as to thus increase the conversion into gasoline. It is thus advantageous to cycle the 35 fixed gases, particularly the Cs’s and C-i’s, re 3 stream is at a cracking temperature to thereby subject the asphaltic material to cracking. 2. In thev conversion of higher boiling hydro carbon oil into lowerboilng hydrocarbons, the process that comprises treating hydrocarbon oil with a solvent of the oil under conditions in 'which the solvent is an anti-solvent of asphaltic mate rial to thereby precipitate asphaltic material con tained in the oil, passing the treated- oil to a cracking Zone wherein the oil is heated in a flow 10 ing stream to a cracking temperature and sub jected to cracking, and introducing the asphaltic precipitate into said flowing stream of oil at a point therein at which the stream is at a crack ing temperature to thereby subject the asphaltic 15 material to cracking. 3. In the conversion of higher boilng hydro# carbon oil into lower boiling hydrocarbons, the process that comprises treating a hydrocarbon charging stock with a liquefied normally gaseous hydrocarbon to thereby precipitate asphaltic ma terial, passing the treated oil to a cracking Zone wherein the oil is heated in a flowing stream to a cracking temperature and subjected to cracking, introducing the asphaltic preciptate 25 into said flowing stream of oil at a point therein at which the stream is at a cracking temperature to thereby subject the asphaltic material to cracking, separating the resultant cracked prod ucts into vapors and residue, fractionating the 30 separated vapors to form a heavy reilux con densate, an intermediate condensate and a final distillate product, and combining the heavy re flux condensate with the charging stock for treatment with said liquefied normally gaseous 35 moved from the final distillate of the process, to hydrocarbon. the solvent tank Il so as to obtain not only the solvent value of the gases in the asphalt re moval step but also to increase the reversion 4. In the conversion of higher boilng hydro carbon oil into lower boilng hydrocarbons, the process that comprises treating a hydrocarbon charging stock with a liquefied normally gaseous 40 hydrocarbon to thereby precipitate asphaltic ma v40 reactions occurring in the cracking zone. While I have described a particular embodi ment of my invention for purposes of illustration, it should be understood that various modifications and adaptations thereof which will be obvious to 45 one skilled in the art, may be made within the spirit of the invention as set forth in the appended claims. I claim: 1. In the conversion of higher boilng hydro 50 carbon oil into lower boiling hydrocarbons, the process that comprises treating hydrocarbon oil with a liqueñed normally gaseous hydrocarbon to thereby precipitate asphaltic material, passing the treated oil to a cracking zone wherein the oil 55 is heated in a ñowing stream to a cracking tem perature and subjected to cracking, and intro ducing the asphaltic precipitate into said flowing stream of oil at a point therein at which the terial, passing the treated oil to a cracking zone wherein the oil is heated in a flowing stream to a cracking temperature and subjected to crack ing, introducing the asphaltic precipitate into 45 said flowing stream of oil at a point therein at which the stream is at a cracking temperature to thereby subject the asphaltic material to crack ing, separating the resultant cracked products into vapors and residue, fractionating the sepa rated vapors to form a heavy reflux condensate, 50 an intermediate condensate and a ñnal distillate product, subjecting the intermediate condensate to further cracking and combining the heavy re flux condensate with the charging stock for treatment with said liquefied normally gaseous 55 hydrocarbon. . ' HAROLD V. ATWELL.