US1420832A - Process for cracking oils - Google Patents

Description

R. p. GEORGE. PROCESS FOR CRACKING OILS. APPLICATION FILED SEPT- 14. I921- Patented June 27, 1922.

2 SHEETS'SHEET I.

H. D. GEORGE. PROCESS FORCRACKING OILS. APPLICATION FILED SEPT. 14. 1921.

Patented Jun 27, 1922.

2 SHEETSSHEET 2.

- gium, Se t.

Canada, ept. 10, 1920; Chile, Oct. 25, 1920;

the production ofother RUSSELL D. GEORGE, OF BOULDER, QOLORADO.

v PROCESS r03 CRACKING on s.

Specification of Letters Patent.

Application filed September 14,1921. Serial No. 500,510.

5 of Colorado, have'invented certain new and useful Improvements in Processes for Cracking Oils, (for which I have filed applications in Argentina, Oct. 25, 1920; Australia,- Oct. 11,1920; Austria, Sept. 25, 1920; Bel- 23, 1920; Brazil, Sept. 30, 1920;

Colombia, Feb. 3, 1921; Cuba, Sept. 29, 1920; Ozecho S1l3ovakia, Sept. 27, 1920; Ecuador,

p 1920; Germany, Sept. 25, 1920; Great Britain, Sept. 14, 1920; Holland, Sept. 14, 1920; Hungary, Sept. 29, 1920; India, Nov.

1, 1920; Italy, Sept. 27, 1920; Jamaica, Oct. v 20, 1920'; Japan, Sept. 29, v1920; Mexico,' 20 Sept. 21, 1920;

Panama, Nov. 10, 1920; Peru, Dec. 16, 1920;Poland, Sept. 24, 1920; Rumania, Sept. 29, 1920; Spain,.Sept. 27,1920; Trinidad and Tobago Nov. 15, 1920; Turkey, Oct. 14, 1920; Venezuela, Dec. 17 1920, and

- 2'5 Union of' South Africa, Oct. 6, 1920), of

,, hich the following is a specification.

This invention relates to processes for cracking oils, particularly for the "production of gasoline, but it is also applicable to hydrocarbons lighter than the oil being cracked. v

The invention has special reference to improvements in the method and apparatus de scribed in my prior applications Serial Nos. 327,428, 2927, 129 and 327,130, filed Sept. .30,

My improved method of operation comprises subjecting to a cracking temperature a substantialbody of heavy oil while incon- 40 tinuous flow throughan upright still keptv full of oil; the delivery of the heated oil to a separating chamber in which the vapors are separated from a body of hot oil maintained in said'chamber; the continuous return of residual oil from' the separating chamber to the still through a carbon separating chamber, from whichthe carbonfreed oi'lis delivered together with rawoil,

' to the lower portion of the still, which is it- 5 0--s'elf provided with means for removing any carbons adhering to the inner wall of the still. The carbon produced by thecrackmg is therefore constantly being removed from x the circulating system. y I have discovered that in order to obtain RUSSELL D. GEORGE,

Oct. 4, 1920 ;.France, Sept.

7 Patented June 27, 1922.

the best results it is desirable that the percentage of free carbon in the stream of circulating oil, as it is delivered to the still, be kept below 1% and preferably as low as .6 of 1%.

f Further features of novelty are the manner in which the temperatures and conditions of condensation in the separating chamber and condensers are. controlled whereby-the'method is made applicable to the treatment of a- Wide'range of oils and the conditions of'operation during the progress of a run can readily be controlled.

The present arrangement renders the whole process flexible and susceptible of successful application to oils of widely different physical and chemical properties. I The process is especially suited and applicable to the treatment of mineral oils. of high boiling point, including crude petroleums, shale oils,.distillates, residual :oils and others,-for the production therefrom of light hydrocarbons such as gasoline and 0t ers suitable for use as fuel in internal combustion engines. It is operated at a pressure ranging from'60 to 120 pounds per square inch, and a temperature ranging from 700 to 850 F., depending upon the character of the oil to be treated. Experience shows that most oils yield the best results when treated at astill pressure between 75 and 105' pounds per-square inch, and a still temperature between 725 and 850 F. For example,-Burkburnett distillate is best treated at a still pressure of 86 pounds per square inch and a still temperature of 745 F.; Eldorado, Kansas, distillate and fuel oil, at .86- pounds' per square inch and a temperature of 755 F.; Pine Island'crude at 86 pounds.

95 "If oil vapor is allowed to accumulate aboyeper square inch and a temperature of 7 80F.

the. body of oilin thestill, the wide difler encefbetween the specific heat'of the oil vairregular distribution of heat in the still. As a consequence, local overheatingand de'- composition of the-vapors areglikely to ocpor and that of" the" ,oil causes a slow and cur. This; results in excessive fixed gas loss and the formation of unsaturated and aro- .matic hydrocarbons. 'I'have found that these difliculties areavoidedif "the still is kept completely full of flowing oilandthe oil is in constant circulation through the a'rotary motion about the" axis of the still,

system. ,By giving the oil within the Sun tion of the heat to the oil is .rapid and uniform. The vapors tending to form within the body of the oil move toward the axis of .the still under the action of centrifugal force and are therefore enclosed in a protecting matrix of oil and are quickly removed from the still. Under these conditions local overheating is impossible, and decomposition into fixed gases and unsaturated hydrocarbons from this cause is avoided.

-Une form of apparatus in which the process maybe carried out is illustrated in the accompanying drawings in which Fig. l is a diagrammatic representation of the plant as a whole;

Fig. 2 is a plan view of the adjustable. insulating section used .on the separator,

Fig. 3 Is, a plan view of the screen in the T coke trap,

' Figftis a sectional view showing the interior arrangement of the coil and baffles in the separator,

'lFig. 5 is aplan and.

Fig. 6 is a plan view of the coil 01.

'Referring to Fig. l, A and A are two storage tanksfor raw oil. 'From the bottom of thetanks, pipes l and 2 lead to the inlet side of a force pump P, which delivers the oil under the requisite pressure into the cold oil service tank B. From this tank, valve controlled pipe-lines, a, b, 0 lead to.

7 view of the baffle plate,

coils f, e, ol, located respectively in the se arator S, and in the two pre-condensers C and PC. These coils d, e, 7, while they may' and preferably do act as re-heaters for the oil to be fed into the sti l, have as an important function, the control of the temperature in the particular condensers in which they are located; The coil d, receives j oil from the tank B from the-pipes c and Z,

and delivers hot oil through pipe a to the hot oil tank C. The coile receives cold oil through pipe I) and delivers hot oil through pi e t to the tank G. a

ot oil from tank C isdelivered. by aninjector I through pipe .9 together with oilv frompipe'n into the lower portion of the still St below .the heated zone thereof. Thestill as shown, is mountedupright within a heating chamber F, provided with suitable gas or oil burners 70. Preferably this chamher is subdivided into sections each having its own burner, with separate connections to the stack 71 -'The inlet ipe s. and exit pipe 4 are located respective y below'and above the heating chamber. e l

The still is provided with a vertical shaft 6, carrying a-helicalscra-per8 driven by a worm'geanlO. .The-scraper 8 engages the inside wall of the-still and is driven in such. direction that; they removed carbon may fall deghlegmation as possible.

neaaeaa 'at about the point indicated-'by'the dotted line .14. The bottom of the separator is preferably conical and connected thereto is the discharge pipe 16 which opens into a 75 carbon or coke trap K. The pipe 16has its opening below the-screen 18 by which the carbon tending tofloat upw'ardis separated. From the upper pontien of the coke trap the oil now freed from carbon passes through 8 the pipe 70. into the pipe 5 wherein it is mingled with raw oil from the hot oil tank (l and the mixture delivered to the still by an injector 1t. I

The coketrap wardly extending portion from which the precipitated carbon can be'blown off through pipe 20. I

, The separator S is preferably provided with heat insulation which may entirely surround the body portion of the separator. Preferably this heat insulation is made in sections 22 each of which is made in sections as shown in Fig. 2 SOyllllitll they can be applied or removed as required.

The separator is shown in detail in Fig. 4. As there indicated there is located above the normal oil level a grooved distributing plate 26 having perforations extending therethrough. Mounted above the distributor 26 .is a delfiecti-ng' plate 28 on to which may flow oi baffle plates 40 having perforations preferably arranged "as shown in Fig. 5,'the perforated plates being so arrange-d that, the perforated portions are located alternately on opposite sides so that afurther tortuous passage is provided/to bring the upwardly'120 moving, vapors into contact with the coola 7 ing coils. still further baffle 37 m ay be used above the coil cl. Any one. or other suitableforms of battle may beused to insure contact with ascending vapors'and any descending joil orcondensate, the object be 1 ing tov obtain as complete rectification or xtending through the top is a'spray nozzle m by which oil maybe delivered into K is provided with a down- 85 f Above the baffle- 36. 110

.the pipe lwhich is in turn connected by the separator. This nozzle is-connectedto branch 0, to the pressure oil tank B; and also by pipe is to the heating; coil 6- in the pre-condenser PC. From the top of the separator S a vapor line 42 leads to the precondenser PC, from which in turn leads-a vapor pipe 44 to the pre-condenser PC. Valved connections 50 and '52 may be used to directly connect the vapor lines 42 and 44 with the final condenser, 48. From the precondenser PC the back run pipe 32;;delivers into the separator and a similar back run pipe 30 is connected to the pro-condenser PC. valved pipe 52 connected to a source of air or gas supply, for a purpose to be described later. A gauge glass 72 connected by pipe 74'to the vapor line 42, indicates the liquid level in the separator S.

' To the pipe 30 is connected a branch pipe 54 leading to the coke trap, and there is also provided a branch pipe 56 between pipes 32 j andx54, so that condensates can be run from either of the pre-condensers to the upper portion. of the coke trap, to be there mingled with the carbon-freed oil on its way to the still.

pipe at, whence oil may flow through pipe Additional temperature control of the precondensers is obtained by delivering raw oil through pipe a from tank B into coil f in pre-condenser PC, thence into the hollow chamber 58, pipe 60, hollow chamber 62 into p into tanks A or A or through pipe .6 into a storage tank (not shown) to which is also connected a delivery pipe 64. There may thus be delivered through this feed line either oil from tank B or from an outside supply. It is preferable to use in this line,

' a high-boilingpoint oil, and ifthe particular oil under treatment contains relatively low boiling point constituents, it may be necessary to use a supply independent of the systom.

66 and 68 are valved delivery pipes by which the condensates,in case they are prod ucts ofdesired composition, may be drawn ofi' directly for use or further treatment.

7 0 is a valve at the end of the system. The desired pressure of the feed oil is obtained by pump P forcing oil into tank B. This tank B and the tank C are'provided with development of excess pressure, oil is returned from these tanks to the storage tanks Aand A.

The various pipes are provided with valves at suitable points, these valves being shown, butnot referred to by specific numerals or reference letters.

The method is carried out as follows: Oil is'fpumped from the receiving tanks into the still and heat is applied until-the requisite pressure is developed. This pres- Also connected to the pipe 30 is a matrix.

sure, may be'obtained by introducing air or .gas through the pipe 52 into the pipe 30.

leading into the interior of the separator.

The preliminarily heated oil from the tankC is delivered into the lower portion 7 forces produced by'the rotation of the carhon-removing helical scraper. The result of this centrifugal action is to cause the heated vapor charged portion of the oil-to pass to the center while the cooler oil is forced into immediate contact with the heated surface of the still, thus making the distribution of the heat in the body of the oil very rapid and uniform,'and thoroughly protecting the vaporslfroni' overheating and consequent decomposition with re sulting developmentof undesirable hydrocarbons including an excess of fixed gases. -When the oil in the still is raised to the cracking-temperature, the expansion of the liquid and formation of vapors cause an upward movement of the oil in the still and the vapors formed are carried upward and out of the heated zone within Sub ected to the action of the centrlfugal the body of oil which forms a protecting .95

This vapor charged oilis then delivered in a stream throu h the pipe 4 into" the separator S at a point well above its bottom and discharged thereinto.

The inner wall of the still is kept free 1 00 i from carbon by means of the helically shaped scraper 8 which deliverswhatever carbon it may scrape off to the settling space at the lower end of the still below the inlet pipe .9. This carbon scraper is similar to that described in -my. above mentioned applications.

There. are thus two carbon set: tling chambers formed at the lower end of the coke trap K and the still St respectively.

The heating of the oil in the'still is thus carried out under the very best conditions to avoid overheating of the, vapors with the resulting formation 'of undesired and undesirable compounds.

The heated oil flowing from the top of the 1 still is delivered intothe separator chamber which isan important and essential featureof my invention.- i

As has been above indicated the separator in its construction comprises a partially heat-insulated vertical cylindrical chamber divided into a vapor space above, and a. liquid oil. space below. This vapor space is provided. with a series of coils through' vapors. This cooling oil may come directly from the 'tanloB or may beoil which has been passed through the coil.e.,- and a series which relatively cool oil is passed undercon-; 12,5 trol to cause a selective condensation of the ticles of condensate? from the vapors not condensable at the temperature in the separator," and distributors to. properly and evenly distribute the condensate over the surface of bath of the hot'oil in the lower.

part of the separator for the purpose of securing the mostefl'ective cracking action; and with means for admitting crude oil above the various battles. The top of the. vapor space is, and apart of the walls may be, leftexposed to the atmosphere to aid condensation. The inlet pipes and 32 provide for the return of the condensate from the first and second pre-condensers to'the separator and a cracking action results from the contact of these cooler oils with the highly heated bath of oils in the separator.

The functions of this separator are that it 20 provides a space for the vapors and vapor charged oils and particles, separate from the still itself, in which they are protected from direct heat and consequent super-heating and decomposition into unsaturated and aroperature and pressure.

matic ydrocarbons and fixed gases, and the waste resulting therefrom. It provides by;

selective and controlled "condensation a supply'of suitable cooler oil which' by the dis- Y trlbutor. is.applied uniformly to the surface of the bath of hot oil in the lower part of the separator, thus furnishing the most satisfactoryconditions for cracking. The rate of condensation is controlled by controlling the rate of flow of oil through the coils; and by exposing to the air varying portions of the upper part of the separator. The. baffles in theseparator remove the suspended and entrained particles of condensate from the uncondensed vapors and prevent them from passing over to the subsequent condensers.-

y the close connection and rapid circula tion from the still to the separator and on to the coketrap, the lower part of the sepa rator contains abath ofoil which is maintained at substantially still temperature, thus furnishingin the best possible form one of the necessary conditions for effective cracking without exposing the vapors to superheating and decomposition.

' Condensation in the upper part of the separator is necessarily accompanied by reduction of volume, and this means reductionflof )ressure. Reduction of pressure is followed.

y expansion and release of vapors from the bath of oil. It will also cause the actual vaporization of particles or oil which were potentially vaporized .but held .in liquid form, by the'pres'sure. This will renew the pressure. Thus there is in the separator an extremely rapid pulsation .or alternation of higher and lower pressure favorable to the cracking process. The separator is one of the units of the cyclic or U-tube circulation by which the oils are circulated, blended, freed 6 from carbon and alternately raised and lowfirst pre-condenser and' there heated to a considerable temperaturebefore it entersthe v i separator coils may be omitted entirely, and

v culated.

Y ijnaasea ered in temperature and returned fresh for further treatment, all of which steps play a v I part in this process of cracking.

By feeding fresh oil by a spray into the vapor space of the separator, a part of the fresh feed oil is-immediatel vaporized without passing through the'still, and the heav less easily vaporized part is blended witi the condensate formed in the upper part of the separator and thrown down upon. the surface of the hot bath of oil, furnishing another condition favorable to cracking by bringing. into contact oils physically and chemicallydiflerent.

' Opportunity is thus afforded for returning to the cracking bath from the pie-condensers one or more condensates of lower boilingpoint than those formed in the separator. l

The whole process is flexible and susceptible of successful application to oils of Widely different physical and chemical properties. Most cracking processes are rigid and inflexible, su'sceptibleof practically no modifications except those of tem The separator also performs the function of heat exchanger b which heat is taken from the vapors an imparted to the feed oil. This saves fuel. The rate of flow of oil through the cooling coils may be modified by the pump, or bythe valve or by both. I f

The oil may be sent throughthe separator only, or it may be sent first through the separator coils. p I I If desired the circulation through the condensation may be dependent upon the exposure ofthe'top and walls of the vapor space. 1

Condensation may be produced or aided by spraying cold feed oil into the vaporspace in Q t e separator. I

By'modifying and regulating the coolingv and condensation the character-10f the ;o il: -f thrown, upon the' cracking bath is correspontlingly modified. I The vapors from the separator pass there-7115 in construction and consist of vertical cylin Q ders containing cooling coils and are sur.

' rounded by hollow chambers 58. 62', through i which oil'or other coolingliquid may be cir- The pre-condenser PC is preferably ro i vided with baffles which may be of any 0 the types shown in connection with the separator S. The second pre-condenser may or may not be battled and is provided with a cooling coil which may or may not be connected with the feed system as. previously explained. Both .pre-condensers are pro into the separator carries some carbon whichit is essential to remove before the oil is re- 'vided with run back pipes by which the conthe proper condensates for the cracking process may be secured, and the undesirable part may be returned to the circulation by way of the coke-trap.

, The removal of all suspended vapor of high boiling point from the vapors which pass on to form the final product in the end condenser.

The control of the end point of the final product through pre-condensing by means of the circulating oils of the cooling system.

They are heat exchangers removing heat from the vapors and transferring it to the feed oils. I i a They also give elasticity and flexibility to. the process, permit wide selection and distribution of the various products formed in the process, and makepossible a perfect control of the end pointand other features of the final product.

They supplement the work of the sepa rator.

If desired the product of these pre-condensers may be drawn OE and used commer- I cially for blending'with casing head gaso line, etc.

With certain oils it may be desirable to use only one pre-condenser, with others two may give best results. It is possible that oils may be encountered which could be best treated by connecting the separator with the vapor line to the main or final condenser.

The heated oil delivered from the. still turned to the still for l e-cracking. This is effected in thecoke trap K into which the carbon charged oil is discharged from the bottom of the pipe 16 with a fairly rapid downward movement which tends to send the heavy carbon grains toward thebottom of the trap. The downward movement of the incoming oil is checked by the body of stagnant oil while the carbon grains, havin a higher specific gravity, are less retarde and sink down to the bottom of thetrap.

The outlet from the trap is far above the orifice of the pipe 16 so that there is a reversal of movement of the oil from the downward to theupward direction, this upward movement being extremely slow. By

, not exceed 1 and pre erably be less of the feed oil. The gasolineyiel desired limit is permitted to lean, the coke trap and enter the still. v

I have found that'it is highly important to the still shall than cred from the coke tra On account of the agitation of the oil in the separator S due to the constant inflow from the still and the separation of vapors, the free carbon carried over from the still or developed in the separator remains in suspension, but a large part of its has become massed into grains of appreciable size,

which greatly facilitates its precipitation into the coke trap below. Theuncracked oil and the above mentioned condensates become thoroughly blended under the agitation in the separator S, said blended'oil being of reduced density and in a'highly liquid condition on account of the light condensates therein. This fact facilitates the separationtherefrom of the suspended car-' bon since the difference between the density ofthe oil and the carbon is increased, and

therefore, the momentum of the downward moving carbon in the trap forces it further cause the oil is more liquid.

There are thus-providedtwo points within the circulating system at each of which carbon is removed, namely the chamber at the lower portion of the still, and the coke trap. These chambers form stagnant pools connected with the main circuit of the moving oil but in which there is substantially no motion. The carbon may be. removed from these settling chambers either continuously or intermittently as desired.

commercial operation of the process in a 60 that the suspended carbon in the oil deliv 1 Following. is a brief description 'of -the barrel still using Burkburnett,.Texas, oil. Y

The Burkburnett crude used is a para base oil having a gravity B. of 39 to 41, and yielding approximately 40per cent natural gasoline having. an end point of 410 F.,-

and about 16 per cent kerosene having a gravity of 42 to 4,4 B. 'The gasoline and kerosene are taken off by the usual methods. After this another'QO per cent istaken ofi as gas oil and wax distillate, which consti tutes the raw material for the cracking. The pressure in the cracking still is kept at 86 pounds per square, inch, and the temperature in the still is held at 745 F. The I temperaturein the bottom of the separator runs 670 F.. while that of the pre-"condenser is 530 F. The temperature of the blended oil returning to the still in pipes, is 615 F.

The fixed gas lossis-less than 1 er cint is etween '7 8 and 79 per cent, by volume of the feed oil. The carbon is taken oif in a'sludge;

like'mass containing about 50 per cent carbon and 50 per cent oil, and measuring 20 per cent by'volume of the feed oil. The

carbon is separated from the oil and the oil! returned to the system. This per cent of the feed oil yields, on cracking, 8 per cent additional gasoline, making the total yield of gasoline 86 to 87 per cent of the feed oil. 10

The gasoline has an initial point of 80 F. and an end point of l10; F, and a gravity of 58-60 Be. The content of unsaturated hydrocarbons does not exceed 3 per cent. The color is water white, and the odor is like that of straight run gasoline. The vaporization curve is regular and constant.

' The gasoline requires no chemical treatment. 7

My invention provides a continuously 0perative method of cracking heavy hydrocarbons into lighter hydrocarbons, all the factors essential to the production of the de- .carbon separator, delivering the cleaned oil from the carbon separator to the still; and

the amount of free carbon in .the cleaned 01 below 1%.

- keepin the amount of free carbon in the cleane oil belowlyo.

2. The process which consists in heating heavy hydrocarbon oils in continuous flow through an upright still to a cracking tem perature; delivering the heated oil from the 3 top of the still to the separating chamber "wherein is maintained a pool of hot oil at a level above the still; permitting the vapors v v to separate from the oil and collecting and condensing the same delivering the oil from the said pool to a carbon separator, deliveringthe cleaned oilfrom the carbon separator to the lower portion of the still and keepin 3. The process which consists in heating heavy hydrocarbon oil in-. .continuous flow through 'an upright still to a cracking temperature, removing separated carbon from the still, delivering the heated oil to a separator chamber wherein is maintained a pool of hot oil; permitting the vapors to separate from the'heated oil and collecting and condensin the same, delivering the oil from the sai pool to a-carbon separator, deliver- .ing the cleaned oil from the carbon separator v naeosae to the still; and introducing raw oil into the oil fedto the still. v

4:. The process, as claimed. in claim three in which rawv oil is introduced into the vapor space of the separating chamber.

' 5. The cyclic process for the cracking of oils for the production of gasoline, comprising circulatlng oils in a closed system, comprising a heated still, separator chamber, and a carbon remover, whereby the oils are brought to a temperature of potential vaporization in the still, the vapors are released in the separator chamber, the free'carbon is removed from the oil in the carbon remover and the carbon freed oil is returned .to the still; maintaining a pool of hot oil in bottom of said separator chamber, conducting the separated vapors to a cooler chamber where the heavier vapors are condensed, supplying new oil to the system by passing said new oil delivering the-condensate into said pool of hot oil.

6. The process which consists in heating heavy hydrocarbon oil in continuous. flow through a still to a cracking temperature, delivering the heated oil to a separator chamber wherein is maintained a pool of hot oil, permitting the vapors .to separate from the hot oil, subjecting the vapors to rectification within the ohamber, andthen'collecting and condensing the same, delivering the oil from said pool to a carbon separator, de-

livering the cleaned oil from the carbon separator to the still, and introducing raw oilv into the oil fed to the still.

7. The process which consists in heating heavy hydrocarbon oil in continuous flow through a still to .a cracking temperature, removing separated carbon from the still, delivering t e heated oil to a se arator chamber wherein is maintained a poo of hot oil; permitting the vapors to separate from the heated oil and collecting and condensing the same, delivering the oil from saidpool to a carbon separator, delivering the cleaned oil from the carbon" separator to the still; and introducing raw oil into the oil fed to .the still.

8. The process'which consists in heating heavy hydrocarbon oil in continuous flow through a still to a cracking. temperature,

removing separated carbon from the still, delivering the heated oil to a separatorj chamber wherein is maintained a pool of hot oil,

permitting the vapors to separate, from the heated oil, subjectin the vapors to rectification within said 0 amber and then collooting and condensing the same, delivering the oil from said pool to a carbon separator,

delivering the cleaned oil from the carbon separator to the still, and introducing raw. oil into the oil fed to the still. In testimony whereof, I 'aiiix m signature.

RUSSELL n. e once.

85 through coils in said cooler chamber; and a

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