US2008661A - Method of treating hydrocarbon oils - Google Patents

Description

`uly 23, 1935. H. v. ATWELL METHOD OF TREATING HYDROCARBON OILS Filed Maron 21, 1953 INVENTOR- "7 v HAnoLo u An/:LL

BY wm a# M ATTORN EY- Patented July 23, i935 unirse stares PATENT ortica METHOD OF TREATING HYDROCARBON OILS Harold V. Atwell, White Plains, N. Y., assigner to Gasoline Products Company, llnc., Newark, N. J., a corporation of Delaware Application March 21, 1933, Serial No. 661,898

4 Claims. (Cl. 196-5l) This invention relates to the production of adapted for recycling through the system. Since lighter products from relatively heavy hydrothe vapors and tar are soaked or digested sepacarbon oil, and pertains more particularly to the rately their temperature may be individually regproduction of gasoline suitable for use as a motor ulated to produce desired results. Separation of 5 fuel from heavy hydrocarbon oil such as crude the fresh charge into the constituents mentionedl 5 petroleum, reduced crude Orth@ like, hereinbefore is preferably effected by introducing It is an object of my invention to provide a the charge directly into the fractionating zone. process whereby fresh charging stock may be The above mentioned and further objects and separated into a relatively light clean cracking advantages of my invention and the manner of stock and a relatively heavy residue of coke attaining them will be made clear in the followl0 forming tendencies, these two stocks being thereing description taken in conjunction with the after separately heated, subsequently comminaccompanying drawing.

gled for digestion and thereafter separated into The drawing indicates in schematic form an vapors and liquid residue which are separately oil treating system embodying my invention.

soaked with the result that additional conversion Referring more particularly to the drawing, 15 of lighter products is attained without detrimenreference numeral l indicates a fractionator, 2 tal deposition of coke or carbonaceous material. a light Oil heater, and 3 a heaVy Oil beaten Fresh In accordance with my invention fresh charg- Charge, which may for example, be crude petroing stock, which may be crude petroleum, reduced leurn such as 35 A. P. I. mid-continent crude crude, or other comparable oil stock is separated oil, is introduced into fractionator l through 20 into a relatively light clean distillate cracking charging line t, by action of pump 5. In the stock and a relatively heavy dirty stock of coke fractionator the fresh charge comes into Contact forming tendencies. These two stocks are heated, with hot vapors and is thereby to a certain exeach one preferably being heated to the maximum tent separated into a light clean distillate stock temperature possible without deleterious coke forwhich is collected on trap out tray 6 and unva- 25 mation, the former because of its cleaner crackporized residue which collects in the base of the ing characteristics being adapted to a higher fractionator. The clean distillate fraction col'- cr'acking temperature than the heavy stock. The lected on the trap out tray is removed through pipe light stock may for example be heated to from 'l and forced by action of pump 8 through the 925 to 975 F., preferably about 950 F., under a coils of the light oil heater or furnace 2 in which 30 pressure in the range of a few atmospheres to the oil is heated to a moderately high cracking 450 pounds per square inch, preferably about 200 temperature sufficient for example to produce pounds per square inch. The heavy oil because from 15 to 20% of end point gasoline per pass, of its coke forming tendencies can be cracked preferably about `15%. This temperature may only toa lesser degree. A` suitable temperature be, for .example from 925 to 975 F., preferably 35 range for this stock would be from 800 to 850 about 950 F. The pressure may vary consider- F., preferably about 825 F., While the pressure ably but is preferably about 200 pounds per might be substantially the .same as that exerted square inch. Additional light oil from an exon the light oil during the cracking thereof, but ternal source may be introduced into line 'l 40 these figures would vary somewhat dependent through pipe 4l to effect a balance of conditions 40 upon the exact character of the oil being treated. or to take care of surplus stock available else- The products of conversion resulting from the where. The heavy relatively dirty residue collect- 'heating of the light and heavy oils are then ed in the base of fractionator l is removed through commingled with aresulting equalization of the line 9 and forced by action of pump l0 through temperature thereof and the commingled prodthe heavy oil heater or furnace 3 in which it is 4,5

ucts may then be subjected to soaking in a comheated to a moderate cracking temperature sufmon zone subsequent to which the soaked `or licient, for example, to produc-e from 8 to 10% digested products are separated into vapors and of gasoline per pass. This temperature may be,

tar. The two latter products are then further infor example, from 800 to 850 F., preferably about dividually soaked'with attendant additional con- 825 F. The pressure may be the same as that 50 version and the resulting digested vapors, includexisting in the light oil heater, e. g. 200 pounds ing those'formed from the tar, are introduced into per square inch, or may be different therefrom a fractionating Zone for separation into a desired in certain instances. Additional heavy oil may gasoline distillate, a cycle stock, and a residue. be supplied from an external source through pipe These two latter products are of a character 4,2, whenever desired to effect a balance of con- 55 ditions or to take care of surplus stock available elsewhere.

The cracked light oil and cracked heavy oil are removed from the heaters 2 and 3, through lines II and I2'respectively, under control of adjustable valves I3 and I4. The two streams join and pass through pipe I5, having valve I6, into soaking coil I1, which is preferably fired suiliciently to maintain a substantially constant temperature Without imparting sufdcient heat to cause deleterious coke formation, but which may be unheated if desired. The mixed oil undergoes further digestion with the accompanying formation of a small percentage of lighter products in the coil and with an accompanying equalization of the temperature of the light and heavy oils. The composite digested stock is carried from the soaking coil I1 into the separating chamber I8 through pipe I9 having control valve 20. In the separating chamber the pressure is preferably substantially the same as that existing in the heaters, allowance being made for the necessary drop in pressure through the soaking coil and connections. This pressure may be for example 1'15 pounds per square inch. Vapors separate from tar or liquidresidue in this 4separating chamber, the former passing off through vapor line 2I into the vapor phase soaking drum 22, which is main- A tained under substantially the same pressure as that of the separating chamber and at only a slightly lower temperature, the vapors therein being subjected to further soaking or digestion with accompanying conversion into lighter products. The soaked vapors pass from the soaking drum through vapor line 23 and reducing valve 24 into the fractionator I, the latter being maintained at a lower pressure, e. g. poundsqaer square inch. With this method of operation by-pass valves 25, 26, and 21, are closed. Reference numeral 43 indicates a valved draw-0E line through which any liquids collecting in the soaking drum 22 may be removed. y

Unvaporized residue or tar is withdrawn from the bottom of the separating drum I8 and is introduced into the tar soaker 28 through line 29.having reducing valve 30. The pressure in thetar soaker is preferably somewhat lower than that of the separating drum I8; this pressure may be, for example, 50 to 150 pounds per square inch. In this soaker the tar'undergoes'additional soaking or digestion but at lower temperature'than prevailing in the vapor phase of soaking drum 22, with accompanying conversion of the products into somewhat lighter fractions.v The lighter products, as fast as formed, pass oi through the vapor line 3| into the fractionator I, the pressure being reduced, if necessary, by means of valve 3|. 'I'he temperature in the tar-'soaker depends somewhat upon the temperature maintained in the preceding apparatus vbut is suitably in the neighborhood of 800 F. Reference numeral 44 indicates a draw-off line through which unvaporized liquids may be removed from the vessel 28.

In the fractionator the various introduced vapors contact with the fresh charge,- aiding in the vaporization thereof, with the resultthat a` portion of the fresh charge is vaporized and deppsited on trap out tray 6 ashereinbefore explained. At the same time a heavy unvaporizable residue is collected in the base of the fractionator and a desired gasoline distillate is rener through line 35 into the top of the fractionator as a refluxing medium.

'I'he temperatures attained by the light and heavy oils in passing through their respective heaters are selected so that a. maximum amount 5 of conversion is attained without undesirable coking of the coils', the light oil being subjected vto the higher temperature on account of its cleaner characteristics. When the two stocks are combined in the soaking coil I1 the heavierr'elatively dirty oil is raised in temperature by contact with the more highly heated cleanoil and added conversion of the heavy oil results during the time interval taken in passing `through the soaking coil. The increased temperature causes more conversion of the heavy oil but any carbon formed is not particularly disadvantageous since the conversion is carried out in a confined stream wherein the velocity of the oil is suiliciently high toA prevent any undesirable deposition of coke. 20 Subsequent to this digestion, because 'of the separation of vapors from liquids taking place in the separating drum I8, the resulting vapors and liquids may be separately soaked further with additional conversion, while not in contact with one another.

Another method of operating is to close the valves I6, 30, and 36, and open valves 25, 21, and 31. The fresh-charging stock then 'enters the system in the same manner as described hereinbefore and light condensate from trap out tray 6 is also treated as already described, as well as the heavy residue from the base of the fractionator. A combination of heated products, which may be treated under the same pressure conditions as already mentioned, are then passed directly through bypass line 38 into the separating chamber I8 which is then preferably maintained under a lower pressure than that of the heating coils, e. g. 50 pounds per square inch, with resulting separation of the cracked products into relatively light vapors and unvaporizable tar or residue.v Not all of the light cracked products are mixed with the heavy cracked products however, only suicient kpassing through line II to maintain the desired temperature of the products in the separating drum I8. This temperature may be for example, 850 to 900 F., but is preferably 875 F. This drum may be operated either in such manner as to form a liquid residue or cokeby maintaining a suitably high temperature. When residue is removed the ow thereof from the drum may be regulated by manipulation of -valve 31.

)The remainder of the light cracked products pass directly through line 39 into the vapor phase soaking drum 22, which is preferably maintained under about the samepressure and temperature conditions as existing at the outlet of the light oil heater 2, e g. 200 pounds per square inch, and 925 F. temperature. The vapors undergo further soaking or conversion in the soaking drum 22 and thereafter pass throughl the line 23 and reducing valve 24 into the fractionator in the same manneras described hereinbefore. The

lvaporsgenerated in the separating drum I8 and and bypass pipe 38 in any desired ratio. The light oil and heavy oil heaters 2 and 3 and soaking coil Il have been indicated as separate and distinct units but this is not necessarily so since all of the various coils might be combined in a single furnace, proper consideration being given to the arrangement of the coils in such manner as to produce the desired temperatures. The soaking coil might be maintained at a proper temperature by convection heat derived from ue gases in those cases where it is desired to prevent a loss in temperature by the oil traveling through the coll.

While I have described a particular embodiment of my invention for the purposes of illustration it should be understood that various modifications and adaptations may be made within the spirit of the invention as set forth in the appended claims.

I claim:

l. The method of treating hydrocarbon oil which comprises thermallyseparating charging oil having light and heavy constituents into a light clean fraction and a residue, separately heating both said clean fraction and said residue to produce as large an amount of conversion of each to lighter products as possible without deletericus deposition of coke, combining the two separately heated oil bodies to produce an interchange of heat therebetween and also a soaking effect, passing the combined products into a vapor separating zone wherein light vapors are separated from heavier residue, separately soaking said vapors and said residue in individual soaking zones, removing vapors from said soaking zones and combining them in a common fractionating zone and segregating a desired gasoline distillate therefrom, and withdrawing the unvaporized liquids from each of said soaking zones and diverting said liquids from the process.

v 2. The process cf treating hydrocarbon oil which comprises introducing crude oil into a. fractionating zone in contact with hot vapors whereby a clean reflux condensate and a residue are formed, separately heating said condensate 'and said residue to cracking temperatures, the former being heated to the higher temperature, combining the separately heated products in a common soaking zone wherein their temperatures are equalized and added conversion to lighter products is accomplished, passing the soaked products into a separating zone wherein separation of vapors from liquids takes place, separately removing said vapors and said liquids to individual soaking zones wherein further digestion thereof takes place and passing digested vaporous products from both of said zones into the saidfractionating zone wherein fractional condensation takes place, removing gasoline vapors of desired boiling characteristics from said fractionating zone, and separately removing unvaporized products from said individual soaking zones and diverting the removed liquids from the process.

3. A process in accordance with claim 2 wherein said clean condensate is heated to a temperature of about 950 F. and said residue is heated to a temperature of about 850 F.

4. A process in accordance with claim 2 wherein heat is added to said common soaking zone in suflcient quantities to maintain substantially constant soaking temperature.

HAR

OLD V. ATWELL.

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