US1828466A - Oil refining - Google Patents

Description

Oct. 20, 1931. c. HE NDERSON 1,828,466-

OIL REFINING I Filed Aug. 12, 1921 Sheets-Sheet ,1

' INVENTOR.

BY 1y Oct. 20, 1931. c L. HENDERSON OIL REFINING Filed Aug. '12, 1927 2 Sheets-Sheet 2 IIIIIIIIIIII INVENTOR.

- ATTORN Y Patented Oct. 20, 193i CURTIS L. HENDERSON, 0F WICHITA, KANSAS OIL BEFINING Application filed August 12, 1927. Serial No. 212,376.

This invention relates to the refining of oils by' cracking processes. Such processes as heretofore practised have always involved the release of considerable quantities of carbon and fixed gases. The deposit of a relatively large volume of carbonhas in fact been considered an essential feature of the cracking reaction. This carbon While useful as it is, in the form of coke, for fuel purposes, nevertheless is a detriment in the cracking operation, limiting the periods of action and imposing losses in the shut-down periods for cleaning-out, etc.

- Special objects of the present invention are to reduce the formation of coke and fixed gases, with their attendant wastes and losses, to produce a. marketable residuum and to improve oil refining operations generally.

- The foregoing and other desirable objects are attained by certain novel features of process, construction and operation as set forth in the following specification, illustrated in the accompanying drawings and broadly covered in the appended claims.

In the drawings, Figure 1 is a broken part sectional and more or less diagrammatic representation of afundamental form of apparatus suitable for practising the invention.

- Figure 2 is a similar view of apparatus 11- lustrating a further development of the invention. e

Figure 3 is a broken detail view illustrating a modified form of pressure reducing means and control.

The invention involves, as one of its main features, the discovery that the'deposit of considerable quantities of carbon is not a necessary accompaniment to the production of lower boiling point'oils in cracking processes and that the lighter products taken off foverhead can in effect be balanced by the heavier products retained in the residuum.

In the practise of the invention, the cracking is effected as one phase of the operation and separation as another phase of the operation, precipitation of carbon being prevented during the cracking by circulating the liquid at suflicient velocity to overcome the precipitation tendency and formation of carbon being prevented in the separating stage 'by dropping the pressure and removing the residuum from the separating zone as fast as the vapor is released. To gain the time required for the cracking operation, the cracking conduit is lengthened sufficiently to compensate for the increased rate of travel. Thus, while the tube still indicated at 3 is shown as of typical design, it differs from the standard constructions in that the overall length of the tubes 4 is sufiiciently greater than in ordinary stills to give the requisite cracking time, with the increased velocity of flow.

The separating chamber shown at 5.is of a size suflicient to facilitate the release ofthe vapors, but because of the fact that no accumulation is permitted therein, may be much smaller in size than the so-called reaction chambers employed in pressure-system cracking.

The transfer line from the tube still to the separating chamber is designated 6.

In the primary or fundamental embodiment of the invention, illustrated in Figure 1, the pressure is reduced at a point in between the end coil of the still and the separating chamber. In the present showing, the recated at 7 in the transfer line, relatively close along and enters into the top of theseparator under reduced pressure. The reduction in pressure, for example, may be from approximately 200 lbs. at the still to about 30 lbs. in the separator.

Some pressure, such as the latter, has been found desirable to enforce the constant discharge of the residuum from the separator. The residuum discharge line is indicated at 8, extending from the bottom of the separator and the vapor line is shown at 9 extending from the top of the separator to the dephlegmator 10. The discharge or withdrawal of the residuum is regulated or controlled so that it is removed constantly and practically as fast'as the vapors are released. The reto the still so that the cracked product flows of keeping the carbon in suspension; The

residuum, therefore, is a high carbon content fuel oil which is a commercially saleable product as such.

The pressure distillate is shown as passing oil from the top of the de hlegmator through a vapor line 11 to a suita 1e condenser 12. A gas separator lsvindicated at 13 for removing the fixed or non-condensable gases, this sep-v arator having a, discharge line 14 for the gas and a line 15 leading to the gasoline stora e. The raw stock is shown as supplied by a feed line 16 to a heat-exchanging coil 17 in the top of the d'ephlegmator, the stock passin from said: heatin coil into the deph egmator at 18 and t e heat exchange bemg controlled by a valved by-pass 19 about said coil.

The reflux leg of the dephlegmator is shown connected at 20 with a hot oil pump 21 connected at 22 with the inlet coil of the still.

The form of apparatus shown in Figure 2 differs from that just described principally ,in, that a second separating chamber is provided, as indicated at 23, and in that the pressure on the oil is reduced at a point in between these two chambers. The reducing valve in this case is shown at 24 in the residuum line 25. v The general principle of operation is the 'same in that the velocity of the oil is stepped up to overcome the tendency to deposit carbon in the tubes of the still, the tubes are of sufiiciently greater length than ordinary to compensate for such increased velocity and provide the necessary cracking time and the oil is continuously removed from the separating chamber to prevent or reduce deposit of carbon therein. The second separating chamber, at thereduced pressure, acts as a flash chamber, the overhead passing ofl through a vapor line 26 and the residuum passing ofi as a commercial fuel oilthrough the residuum line 27.

The second view illustrates also the possibilities of positively drawing off from the second separating chamber either the over- 'head orthe residual oil, or both, for inhead from the second separator. The pres-t sure distillate goes oif from this mixer through a vapor line 34 to a suitable condens or 35, discharging into the receiver and the entirely e pended in the form of fuel oil.

,oil is taken ofi at the bottom by connection 36 and passed by the pump 37 through the feed line 38 to the top of the dephlegmator, which last connection corresponds in its effect with the feed line 16 in Figure 1.

With the apparatus constructed as disclosed and the process carried out as described, the carbon is largely retained in the residual oil, the residual oil is a commercially saleable fuel oil, the proportion of fixed gases is materially reduced and while in the commercial practise of the invention thus, far, some carbon is precipitated in the separating chamber or chambers, this deposit is so .much less that the system can be ke t in operation without shut-down for muc longer periods than has heretofore been possible under approved continuous pressure systems.

Each embodiment of the invention illustrated has certain advantages. In the second form, it will be observed that a part of the vapor is removed from the system at the top of the mixer or gas oil condenser 33 so that a portion of the gasoline is taken out without having to pass it through the dephlegmator tower. By preventing accumulatlon of oil in the first separating chamber and drawing it off immediately to the second or low pressure chamber, where pressure and temperature are both reduced, there is no subjection of the oil to the higher cracking conditions which have heretofore obtained inpressure systems and as a consequence, deposlt of carbon is almost iminated. The removal of the heavy oil from the high pressure zone practically as soon as it is formed, stops the action which otherwise would convert this heavy oil into coke and fixed gas and keeps the coke sus- The mixing second separator-with the raw oil introduced in the as oil condenser materially increases the refiux of the gas oil taken off from the ratio throughthefurnace. Because of the,

greatly lengthened operating cycles, the wear and tear on the apparatus is very materially reduced'and operating expenses are cut down. The action also is smoother and more nearly automatic and in actual operation a higher percentage of gasoline in the pressure distillate as compared with existing pressure systems, has been obtained.

The fuel oil is a usable product for industrial purposes and so can be taken out of the system in larger quantities than heretofore, at a profit, considering that the carbon is saved and made use of by keeping it in the liquid state in this oil. The apparatus as a whole is relatively simple, all the heat being applied at but one point; that is, at the pressure still, which except for the lengthening of the tubes and clearance provided for increased oil velocity, may be of generally standard construction.

It will be obvious to those skilled in this art that certain changes and modifications may be made without departure from the true spirit and broad scope of the invention. Thus for example, the pressure reducing valves may be of the automatic self-regulating type as shown at 7 and 24 in Figures 1 and 2 or as an alternative, manually controlled means may be used for the purpose, such as illustrated in Figure 3. In this last mentioned view, the transfer line 6 is shown as branched at 39 and as having in these branches the pressure reducing contracted throats 40, 41, controlled respectively by valves 42-42, 4=3-A3. These throats are indicated as of different sizes and the valves enable them to be used interchangeably, or both at the same time, and in the latter event, one more or less than the other. These reducing throats are designed so that stoppage will not occur therein, but the presence of the two branches is an advantageous service feature in that there is always a reserve branch to be used in case of any choking in the other;

What is claimed is:

1. Aprocess of cracking oil which comprises heating hydrocarbon oil to cracking temperature under pressure in a long cracking coil to crack the oil extensively while flowing the oil through said coil at a sufficiently rapid rate to carry out the carbon formed in suspension, passing the cracked o1l and suspended carbon into the upper portion "of an enlarged zone to effect the separation of the light cracked products by distillation,

removing the separated vapors, separatelywithdrawing the liquid from said enlarged zone at a rate adequate to prevent accumulation of substantially any oil therein, stripping the lighter fractions of the discharged residual oil by suddenly expanding it at low pressure into a flash chamber where copious vaporization by its contained heat takcs place, and withdrawing a high grade fuel oil from the bottom of said flash chamber.

2. A process of cracking oil which comprises charging a stream of hydrocarbon oil once through a cracking coilmaintained under cracking temperature and pressure at sufficient velocity to carry the carbon resulting from cracking therein out of the coil without deposition, curtailing further cracking of liquid constituents and separating the light cracked products by delivering the carbon-containing oil into an enlarged chamber where no substantial accumulation of liquid oil is permitted, the residual carbon-containing oil being rapidly discharged therefrom and from the cracking systemto preventaccumulation of liquid in'said chamber, removing the vapors from said chamber, separating out the heavier constituents thereof by partial condensation, expanding, the discharged residual oil at low pressure into a flash chamber to vaporize the lighter constituents by the contained heat of the oil, withdrawing the heavier bottoms from the flash chamber as fuel oil, mixing fresh charging stock with the overhead vapors from said flash chamber, removing the lighter constituents of the mixture as vapors, and introducing the preheat-j ed mixture and the hot condensate from said initial partial condensation into the coil to be cracked therein.

3. A process of cracking oil which comtor to condensate out the heavier constituents as a condensate, discharging the heavy carbon-ladened residual oil from said chamber at a sufliciently rapid rate to substantially prevent accumulation of liquid in saidchamber while delivering saidresidual oil into a' flash chamber under low pressure where the contained heat of the oil efiects copious vaporization thereof, discharging the heavy unvaporized liquid from the flash chamber, partially condensing the overhead vapors from said flash chamber by mixture with a stream of charging 'oil While distilling off the light er constituents of the charge oil, removing the combined light vapors from said mixture, charging the unvaporized portions of said mixture in preheated condition into said dephlegmator and introducing the heavier portions of said preheated mixture and said coil to be 'crackedfitherein.

4:. A process of cracking 011 which com prises cracking hydrocarbon oil under heat and pressure, distilling ofl the light cracked products as vapor, expanding the unvaporized residual oil with carbon in suspension into a flash chamber at substantially atmospheric pressure where the lighter constituents are distilled off by the contained heat thereof, discharging the heavier unvaporized carbon-containing oil as fuel oil from the bottom of said flash chamber, assisting the removal of vapors from the flash chamber by injector action from a stream of charging oil injected into and mixing with the overhead vapors from the flash chamber, removing the lighter constituents of the mixture as vapors and delivering the preheated heavier liquid constituents under pressure to the cracking zone.

5. A process of cracking oil which comprises heating to cracking temperature a stream of hydrocarbon charging oil, mixed only with clean condensate produced in the process, to the desired extent as it flows under pressure through a cracking coil with sufficient rapidity to prevent deposition of carbon therein, delivering the efflux from said ,coil without material pressure reduction into an enlarged unheated chamber where vaporization takes place and accumulation of liquid is substantially prevented by the rapid and continuous discharge of residual oil therefrom at such a rate as to prevent said residual oil from remaining in the chamber fora sufficient length of time to permit the formation of carbon therein, reducing the pressure materially on the discharged residual oil and distilllng it under its contained heat to leave a liquid fuel oil of small carbon content, subjecting the vapors evolved in the enlarged vaporizing chamber to reflux condensation, and returning the condensate upmixed with residual oil to the cracking coil for further cracking.

6. A process of cracking hydrocarbon oil which comprises heating the oil to cracking temperature as it flows under superatmosheric pressure through a heated coil, passmg the oil thence into an enlarged reaction chamber maintained under superatmospheric pressure wherein separationof vapors and liquid occurs removing the separated vapors, withdrawing liquid from said Evenlarged chamber at a rate adequate to prevent accumulation of liquid therein and expand ing the liquid thus withdrawn directly intoa flash chamber and'elfecting distillation by means of the contained heatof said liquid under reduced pressure.

7. A process of cracking hydrocarbon oil which comprises subjecting the oil to. cracking temperature under supera'tmospheric pressure as it flows through a heated coil, passing the oil thence into an enlarged reaction chamber wherein without any material reduction in pressure separation of vapors and liquid occurs, removing the separated vapors, withdrawing liquid from said enlarged chamber at a rate adequate to prevent accumulation of liquid therein and expanding "the liquid thus withdrawn directly into a I flash chamber and effecting distillation by means of the contained heat of said liquid under reduced pressure.

8. A process of cracking hydrocarbon oil ducin the heated oil into the top of an ention of liquid therein andexpanding the liquid thus withdrawn directly into a flash chamber and effecting distillation by means of the contained heat of said liquid under reducedpressure.

In testimonywhereofll have signed my name to this specification this 16th day of Jul 1927. Y

, CURTIS L. HENDERSON.

wherein the oil is raised to a cracking temperature as it flows through a heated coil, is passed thence into anenlarged reaction chamber from which vapors and liquid are separately removed and return of the latter to said coil prevented and the vapors subjected to fractionation to form a condensate which is returned to the heating coil, the process that comprises withdrawing the liquid from said enlarged reaction chamber at a rate adequate to prevent accumulation of liquid therein and'expanding the liquid thus withdrawn directly into a flash chamber and effecting distillation by means of the contained 'heat of said liquid under reduced pressure.

,9. A process of cracking hydrocarbon oil which, comprises heating the oil to cracking temperature as it flows under superatmospheric pressure through a. heated coil intro- Oil V DISCLAIMER 1,828,466.-Cu7'tis L. Henderson, Wichita, Kans. OIL REFININGQ Patent 'dated October 20', 1931. Disclaimer filed March 28, 1935, by thejassignee,

Gasoline Products Company, Inc. I j Hereby enters this disclaimer to claim 9 of the aforesaid LettersPatent which is inthe following words, to wit: I y

' 9. A process of cracln'ng hydrocarbon oilwhich comprises heating the oil.

to crackin' temperature as it flows under superatmospheric pressure through a; heated coil intro ucing the heated oil into the top of an enlarged reaction chambenn lain I tained under superatmospherio, pressure" wherein separation of vapors and liquid 3 occurs, removing the separated vapors, withdrawing the precipitated liquid from. the

bottom of said enlarged chamber at a point remote from that of the introduction of the oil to the chamber and at a rate adequate to prevent accumulation of liquid therein and expanding the liquid thus withdrawn directly'into a flash chamber and effecting distillation by. means of the contained heat of said liquid under reduced pressure! p 0 7ml Gazette April at, 1935.1

DISCLAIMER 1,8 28,466.Ow't"is L. Hcnderson, Wichita, Kans. OIL REFINING. Patent dated October 20, 1931. Disclaimer filed April 25,1936, by the asslgnee, Gaso lme Products Company, Inc. Hereby enters this disclaimer to claims 3, 6, 7, and 8 of the aforesaid Letters Patent. a v

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