US1979532A - Hydrocarbon oil conversion - Google Patents

Description

Nov. 6, 1934. N. G. DE RACHAT HYDROCARBON OIL CONVERSION Filed Jan. 26, 1931 2 Sheets-Sheet 1 INVENTOR NICHOLAS C. DE RACHAT BY ATTORNE Nov. 6, 1934- N. G. DE RACHAT HYDROCARBON OIL CONVERSION Filed Jan. 26, 1931 2 Sheets-Sheet 2 FIG. 2

Patented Nov. 6, 1934 I PATENT OFFICE 1,979,532 HYDROGARBON on. CONVERSION Nicholas G. de Rachat, Chicago, 111., assignor to Universal Oil ProductsCompany, Chicago, 111., a corporation of South Dakota Application January 26, 1931, Serial No. 511,139

' 3 Claims. (C1.-196-49) This invention relates to the treatment of hydrocarbon oils and refers more particularly to the treatment of cracked residues to produce coke-like particles therefrom. 4

5 More specifically, the invention contemplates the treatment of heavy liquid residues produced in processes employed for the conversion of heavy hydrocarbon oils into lighter oils of lower boiling point range. These liquid residues, which are commonly of a pitchy or asphaltic nature, and which may contain highly carbonaceous particles in suspension, may be subjected to heat, devolatilized and partially oxidized by contact with hot furnace gases, as will hereinafter be described, In the production of maximum yields of low boiling hydrocarbons, cracking processes are frequently operated under conditions of tempera- 'ture and pressure of such proportions as to result in relatively severe or' intensive cracking, with the-production of only fixed gases and solid residues other than the desired low boiling point gasoline fractions. When such operations are effected, great mechanical difficulties are encountered, due to the coke deposition tending to plug or stop-the various lines and valves of the system, and its removal at intervals from settling drums is consequently necessary for continuous operation of such processes. The residues thus produced are consequently ,of varying density, hardness and porosity, depending upon the conditions attending their formation and deposition, and are frequently only utilizable as a cheap grade of fuel. For example, the coke removed from the lower portion of a chamber may be found to be soft or hard, depending upon whether liquid charging oil was present in the chamber when the cracking plant was shut in and conversion conditions commenced. Succeedingstrata may also vary, due to comparatively slight fluctuations in the temperature and pressure employed, so that the total amount of coke removed from the chamber may be of a'distinctly non-homogeneous character, varying from soft and easily pulverizable portions which require special blowers for their eflicient combustion, to relatively hard lumps, re-

sembling coal, which must be separated from the 'softer material and. burned in separate equip ment.

In cracking plants not designed for crackingjo coke, the problem of producing maximum yields of gasoline with minimum production of coke presents itself. Endeavors to attain this condition sometimes result in the production of resi-' dues which contain appreciable amounts of carbonaceous or coke-like particles which render the liquid difficult to use in ordinary atomizing burners.

The present invention, therefore, is concerned with improved methods and means for the controllable production of finely divided carbon or coke-like particles of a uniform and lamp blacklike character, with the attendant feature of increased production of gasoline fractions.

In one specific embodiment of the invention, heavy liquid residues-from cracking operations may be discharged at a fixed rate onto atomizing u means comprising rapidly revolving horizontal discs disposed on a shaft co-axially supported in a vertical cylindrical treating chamber, hot flue gases from the cracking furnace being introduced in concurrent flow with the atomized liquid, the coke particles separated from the resultant gases in suitable settling space and the gaseous mixture stripped of its low boiling point hydrocarbon fractions after indirect heat exchange with incoming raw charging stock to the cracking process.

Other. and further objects and advantages of the invention will become apparent from thefollowing description and diagrammatic drawings, 30 in which,--

Fig. 1 is a side-elevational view of one form of apparatus in which the invention may be carried out; and

Fig. 2 is a vertical, cross-sectional view of a form of coking apparatus which may be employed in the 'processs.

Referring to the drawings, heavy hydrocarbon oil to be cracked may be passed via a line 1, controlled by a suitable valve 2, to a pump 3, and discharged therefrom into a line 4, controlled by a valve 5, and passed through an indirect heat exchanger 8, wherein the oil may be preheated by the gases passing therethrough in a. heated state from a coking chamber to be hereinafter more particularly described, said oil, in turn, serving to cool said gases. The preheated oil may be passed from said heat exchanger 8 through a line 9, controlled by a valve 10, into a line 6,

controlled by a valve 7. Said line 6 may comcombined in a line 11, controlled by a suitable valve 12, andmay be passed into a line,13, controlled by a valve 14 leading to a fractionator 29 of any conventional type or combination of equipment adapted to effect separation of cracked vapors into light and heavy portions, or into a no line 15', controlled by a valve 16, leading to a pump 1'7 discharging into a line 18', controlled by a valve 19' into a heating element 20 disposed within a suitable furnace 21, as desired. Insufiiciently converted intermediate portions from fractionator 29 may be withdrawn therefrom for retreatment, through a line 18, controlled by a valve 19, leading from the lower portion of said fractionator, and may communicate with said line 15 leading to pump 17, so that a mixture of raw oil and. relatively heavy, insufficiently convertedfractions may be introduced into the conversion zone or heating element 20.

After passage through heating element 20, wherein suflicient heat and pressure may be maintained to promote conversion of the oil passing therethrough, the heated products may pass through a line 22, controlled by a valve 23, to an enlarged chamber 24, of any conventional type, where further reaction may occur. Vapors from said reaction chamber may then pass through a line 27, controlled by a valve .28, to said frac-' tionator 29.

Unvaporized liquids from reaction chamber 24 may be released through a line 25, controlled by a valve 26 and a valve 26, for discharge into a coking chamber 40, insulated, preferably, by any suitable material, as at 40' in order .to maintain relatively high temperatures during the coking period and prevent a consequent severe heat loss. Within chamber 40 may be suitably disposed a plurality of discs 47, integrally mounted on a powered shaft 46 disposed substantially throughout the central portion of said chamber, and adapted to rotate through communication with any desired motivating means 45 disposed in the upper part of said chamber. The lower portion of said shaft 46 may be suitably disposed within a bearing member 50. A plurality of cones 48 may be also disposed within said chamber 40, so as to efiectively'direct partially treated materials back to the center of the chamber for further atomization through contact with succeeding discs disposed at lower levels throughout said chamber.

As an additional feature of the invention, flue gases, preferably from the cracking furnace, may be introduced through a line 41, controlled by a valve 42, intothe upper section 43 of said chamber 40, separated from the main coking chamber by means of a perforated plate 44, the latter plate serving to evenly direct and distribute the gases in their downward flow through said chamber. Liquid materials on entering .said chamber 40 through said line 25, fall upon the discs 47. and

are thrown violently, due to the centrifugal action point, with the resultant formation of coke par- .ticles of any degree of subdivision.

The gases and solids from the final or lowest atomizing zone may pass into a space 51, divided by a cone 51', where final'separation of solid carbonaceous particles and gases may occur, the

separated gases being withdrawn through a line 52.- In order to efi'ect continuous removal of settled solids in the lower part of said chamber 40, an exit line 59 may be provided, within which may be disposed a suitable screw 58, actuated by powered gears 60, through any desired source of power (not shown) By proper manipulation of the screw 58, a slight level may be maintained in chamber 40, and exit line 59 which may effectively seal the bottom of said chamber and prevent the escape of vapors therefrom.

It will be evident from the foregoing description of the coking chamber, that it is adapted to produce coke particles of a size and quality which may vary over a wide range. By the use of large amounts of flue gas and rapidly revolving discs and the resultant fine atomization, lamp black may be produced, and, with less severe conditions, a uniform grade of coke particles adapted to be burned as breeze coke may be obtained.

. The gaseous mixtures leaving through line 52 may contain substantial quantities of low boiling hydrocarbon fractions, and may pass through a valve 53 to heat exchanger 8 wherein they may flow countercurrent to the flow of oil charge to the cracking process, as previously described. Such portions of the gaseous mixture passing through said heat exchanger as may condense due to cooling by heat exchange with the charging oil flowing therethrough, may be withdrawn from said heat exchanger through a line 56, controlled by a valve 57 and passed to a receiver 70, to be hereinafter more fully referred to; and the gaseous portions still remaining in said heat exchanger may be withdrawn therefrom through a line 54, controlled by a valve 55, and pass into a line 61, controlled by a valve 62, leading to an absorption tower 63 of any conventional type. A suitable cooling and absorbing media may be introduced into said absorption tower 63 through a line 64, controlled by a valve 65. Stripped gases may be withdrawn from said absorption tower through a-line 66, controlled by a valve 6'7, and passed to storage. while absorption liquids containing substantial amounts of gasoline hydrocarbons may be withdrawn from, said tower through a line 68, controlled by a suitable valve 69 to a receiver 70. Receiver 70 may be provided with a line 71, controlled by a valve .72, through which fixed gases may be removed, as well as a line '73, controlled by a valve '74 for the eduction of liquids for redistillation in subsequent equipment (not shown) of the process.

Vapors from fractionator 29 may pass through a line 30, controlled by a suitable valve 31, into a condenser 32, wherein cooling is effected, the cooled and partially liquefied products issuing from said condenser thence passing through a line '33, controlled by a valve 34, into a receiver 35. Uncondensed vapors and gases may be withdrawn from said receiver 35 through a line 36, controlled by a valve 37, and introduced into absorbing tower 63 via line 61 in communication with line 36. Liquid products, containing substantial quantities of gasoline boiling point hydrocarbons may be removed from receiver 35 through a line 38, controlled by a valve 39, and passed via said line to run-down line 73 issuing from receiver '70, effecting a combining of the products from receiver 35 and 70, so that gasoline fractions from the cracking and coking processes may be recovered simultaneously in the subsequent distillation process.

Conversion temperatuiesemployed may range from about 750 to 1050 F., more or less, while pressures employed may preferably be of substantial superatmospheric order, although atmospheric, or even sub-atmospheric pressures may be employed, as desired, depending upon the nature of the charging stock under treatment.

As one example of the results obtainable by an adaptation of the principles of the present invention, a 25 gravity topped crude, characteristic of the Mid-Continent producing area, was

cracked to produce approximately 55% of hydrocarbons of gasoline boiling point,'and about 35% of heavy residual liquids of a nature bordering on extremely heavy asphalt, which must be maintained in a relatively highly heated condition in order to keep it fluid. This residue was discharged into a coking apparatus substantially similar'to that described and treated by the process of my invention, with a resultant produc-' tion of finely divided breeze coke equal to apthrough a heating zone and heating the same i therein to cracking temperature under pressure, introducing the hot oil stream to a reaction zone maintained under cracking conditions of temperature and pressure, continuously removing vapors and unvaporized oil while still hot to a coking zone and impinging the same against a rapidly rotating surface therein to impart centrifugal velocity to the unvaporized oil, introducing to the coking zone highly heated gases of sufficient temperature to coke the unvaporized oil,

contacting the gases with the unvaporized oil in the coking zone and distilling the unvaporized oil to coke therein, and removing the. coke and the vapors and gases from the coking zone.

2, The process as defined by claim 1 further characterized in that the unvaporized oil is passed in a generally downward direction through the coking zone and, during its downward movement therethrough, successively deposited upon additional rotating surfaces at intervals in the path of downward movement.

3. The process as defined by claim 1 further characterized in that the unvaporized oil is passed in a generally downward direction through the coking zone and, during its downward movement therethrough, successively deposited upon additional rotating surfaces at intervals in the path of downward movement, the process being still further characterized in that said highly heated gases are passed downwardly through the coking zone concurrently with the unvaporized oil.-

, NICHOLAS G. DE RACHAT.

Images