US2270086A - Conversion of hydrocarbons - Google Patents

Description

Jan. 13, 1942. J. D. sr-:GUY

CONVERSION OF HYDROCARBONS Filed Feb. 24, 1939 Om mN\ mvv f mzoN mm www INVENTOR JEAN DELATTRE SEGUY `ATTORNEY Patented J an. 13,1942

l 2,270,086 ooNvERsroN or RooAaoNs Jean Delattre Seguy, Chicago, Ill., assigner to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application February 24, 1939, Serial No. 258,246

3 Claims.

The invention relates specifically to an improved process for converting hydrocarbon oils into high yields of good antiknock gasoline by a combination of interdependent and cooperative steps involving thermal cracking of the oil and A polymerization of the relatively heavy olenic components of the normally gaseous products of the cracking operation.

One specific embodiment of the improved. process herein provided comprises subjecting hydrocarbon oil charging stock of relatively wide boiling range to substantial vaporization, separating the resulting vapors and unvaporized oil, pyrolytically cracking vthe vapors in a vaporphase cracking step, separately cracking the `un vaporized oil in a mixed phase pyrolytic cracking step, separating non-vaporous residue from the vaporous components of the products of each of said cracking steps, fractionally condensing said vaporous components in commingled state to separate the same into relatively light and relatively heavy intermediate liquid products, gasoline and normally gaseous fractions, returning said relatively light intermediate liquid products in vaporous state to the vapor-phase cracking step, returning said relatively heavy intermediate liquid products to the mixed phase cracking step, recovering said gasoline, separating from said normally gaseous fractions selected relatively vlight components substantially devoid of readily polymerizable olefins and selected relatively heavy components rich in polymerizabl olens, subjecting the latter to polymerization treatment to effect conversion of said olens into liquid polymers boiling within the range of gasoline, separating the `resulting polymer gasoline from unconverted gases, heating regulated quantities of the latter and regulated quantities of the aforementioned relatively light gases to a high temperature, thereafter commingling the same, at a temperature and in quantities suiiicientto eiect vaporization of the materials supplied to the vapor-phase cracking step, with the charging oil and with said relatively light intermediate liquid products and supplying the resulting vaporized components of the charging oil, vaporv rating and fractional condensing zone I3, which ized intermediate liquid products and gases in commingled state to said vapor-phase cracking step.

vThe invention is, however, not limited to the en- While no novelty is claimed for the various intire combination of process steps disclosed and above recited since there are several cooperative and advantageous combinations disclosed which involve less than the entire combination.

vThe accompanying illustration is essentially a flow diagram of the process provided by the invention 4and the following description thereof will serve to more clearly illustrate' the provisions of the invention and the various non-equivalent alternatives to the specific embodiment, above outlined, which are within the scope of the invention.

Referring to the flow diagram, charging stock for the process, which may be any desired type of hydrocarbon oil ranging from crude petroleum, topped or reduced crude and the like to light distillate, is supplied through line I and valve 2 to vaporizing zone 3 wherein it is commingled, as will be later described, with light gases which have been previously heated to a temperature sufiicient to eiect vaporization of all or a substantial quantity of the charging oil, depending upon its boiling range characteristics. Selected intermediate liquid products of the process which are also supplied to zone 3, as will be later described, and are similarly vaporized therein. When the oils supplied to zone 3 contain high boiling fractions unsuitable for vaporphase cracking, temperature and pressure conditions are maintained in zone 3 under which these high boiling fractions remain unvaporized therein'.

-Any suchremaining unvaporized components of the oils supplied to zonel 3 are separated from the vapors and removed through line 8, while the relatively clean vapors and commingled gases are directed'throug'h line 9 and valve I0 -to vaporphase cracking zone 4.

The commingled vapors and gases are vheated in the vapor-phase cracking step to a high cracking temperature adequate to effect their con Version into high yields of good antiknock gasoline and the products .of this step are directed therefrom through line Il and valve l2 to sepawill be later described. l

When vapors and unvaporized oil are separated, as above mentioned, in zone 3, the unvaporized oil from this step may be removed, all or in part, from the system through valve It in line 8 to cooling and storage or elsewhere, as desired, or this material may, when desired, be directed, all or in part, through line l5 and valve i6 to a mixed-phase cracking zone Il wherein it is heated to an independently controlled cracking temperature, preferably at substantial superatmospheric pressure, either alone or in commingled state with selected relativelyheavy fractions of the intermediate liquid products of the process, which latter may be supplied to zone I1 as will be later described. The resulting conversion products are discharged from zone I1 through line I8 and may be directed through valve I9 to the same separating and fractional condensing zone to which the products from the vapor-phase cracking step are supplied, or, when it is desired to avoid commingling of the non-vaporous residual products of the two cracking steps, the conversion products from zone I1 are directed through line and valve 2| to an independent separating step 22 wherein their vaporous and residual liquid components are separated, the latter being removed therefrom through line 23 and valve 24 to cooling and storage or elsewhere, as desired, while the vapors are directed through line 25, valve 26 and line I 8 to fractional condensation in zone I3.

The conversion products supplied to step I3 are separated therein in the particular case here illustrated into residual liquid, selected relatively light and relatively heavy intermediate liquid conversion products, gasoline and gases which latter are further separated into selected relatively light and relatively heavy fractions. The residual liquid is removed to cooling and storage or elsewhere, as desired, through line 21 and valve 28. The relatively heavy fractions of the intermediate liquid products are removed from step I3 through line 29 and may be discharged, all or in part, from the system to cooling and storage or elsewhere, as desired, through valve 30 in this line or they may be directed, all or in part, through line 3l and valve 32 to the mixed phase cracking zone I1 and therein subjected to further cracking either alone or in commingled state with unvaporized oil from zone 3.

The selected relatively light fractions of the intermediate liquid conversion products are separately removed from step I1 through line 33 and directed through valve 34 in this line to vaporizng zone 3 wherein they are partially or completely vaporized, depending upon the temperature and pressure conditions employed in this zone, and wherefrom the resulting vapors are supplied, with vaporous components ofthe charging oil, to the vapor-phase cracking zone 4.

As an alternative to the method of operation above described, the total intermediate liquid conversion products may be directed from zone I3 through line 58 and valve 59 to vaporizing and separating zone 3, wherein their low boiling components are vaporized and wherefrom they pass, with vaporized components of the charging oil, to vapor-phase cracking zone 4, while their heavier unvaporized components commingle with the unvaporized components of the charging oil and are removed therewith from zone 3 through line 8.

The cracked gasoline product is separately removed from step I3 through line 35 and valve 36 to storage or elsewhere, as desired. This gasoline product is preferably of controlled vapor pressure and may include regulated quantities of dissolved relatively heavy gases. The remaining gases, which include both relatively light and relatively heavy fractions are further separated into selected components for separate further` treatment within the system. One selected fraction of the gases, comprising essentially relatively heavy components rich in polymerizable olens, is removed from the separating step through line 31 and directed through valve 3B in this line to 75 polymerizing step 39. This material preferably is rich in readily polymerizable oleflns such as propene and/or butenes.- as well as corresponding paraiiins and when desired may also include appreciable quantities of light, normally liquid fractions such as pentenes and pentanes. The composition of the materials supplied to the polymerizing zone will depend upon the nature of the separation effected in zone I3 and may be regulated to suit requirements, various methods of accomplishing this being well understood in the art.

'I'he polymerization stock is subjected in zone 39 to conditions under which readily polymerizable olenic components thereof are converted into normally liquid fractions boiling within the range of gasoline. Preferably, this is accomplished in the present invention by heating the polymerization stock and contacting the heated stock with a polymerizing catalyst at the temperature and pressure conditions required to effect the desired conversion. The resulting products are supplied from the polymerizing zone through line 40 and valve 4I to condensing and separating zone 42 wherefrom the condensed polymer gasoline is withdrawn through line 43 and valve 44 to storage or elsewhere, as desired, and wherefrom the uncondensed and undissolved gases, consisting essentially of unconverted parain'nic components of the polymerization stock, are withdrawn through line 45. These gases may be removed, all or in part, from the system through valve 46 in this line or they may be directed,'al1 or in part, from line 45 through line 41 and valve 48 to heating zone 49, the purpose of which will be later described.

The lightest components of the gases separated from the other normally gaseous products of the process in zone I3 are Withdrawn therefrom through line 50 and may be removed, all or in part, from the system through valve 5I in this line or they may be directed, in regulated quantities, through line 52 and valve 53 to heating zone 49. The composition of this gaseous stream may be regulated to suit requirements by controlling the separation effected lin zone I3. Incase it is desired to produce a gas of high hydrogen content for use in a conjointly operated hydrogenating system or the like, not illustrated, separation in zone I3 is,preferably controlled to include substantially only hydrogen and hydrocarbon gases having only one carbon atom to the molecule in this product. When the separate production, as above described, of a high hydrogen-containing gas is not desired, the light gaseous stream removed from zone I3 may include substantially all of the light gases having two and less carbon atoms to the molecule and, when it is not desired to include any or all of the three carbon atom gases in the polymerization stocks supplied to zone 39, allor regulated quantities of these fractions may also be included in the light gas stream removed from zone I3 through line 50. Preferably, when the light gaseous stream removed from zone I3 through line 50 is not supplied, at least in part, to heating zone 49, a separate stream of relatively light fractions comprising the components of the process gases intermediate the stream removed through line 50 and that removed through line 31 is withdrawn from zone I3 through line 54 and directed through valve 55 in this line to heating zone 49.

The gases supplied to heating zone 49 are therein heated to a relatively high temperature ,peratures within substantially the same range adequate to eect the desired degree of vaporization of the intermediate liquid products and cnargmg stock supplied to zone 3 upon com- `mmgiing of tneseoils therein with the heated gases which are supplied from lzone 49 to zone a1, through hne 56 and valve 51. The gases thus supplied to zone 3 pass with the vapors formed in this zone throughA line 9 and valve I0 to the vapor-phase cracking zone 4.

ine range of operating conditions which may be employed to successfully conduct the process of tne invention are approximately as follows: rl'he temperature employed in the vapor-phase cracking step will depend upon the nature of the vapor-gas mixture supplied thereto and may range, for example, from 900 to 1l00 F., or more, preierably with substantially atmospheric or relatvely low superatmospheric pressure in this zone, the temperature and pressure conditions being correlated to maintain the materials undergoing, treatment in this step substantially com` pletely vaporized. The temperature employed in the mixed phase cracking step may range, for example, from 800 to. 950 F., or thereabouts, preferably with a superatmospheric pressure of from 100 to 500 pounds, or more, per square inch. More severe cracking conditions will be employed in this zone when only intermediate liquid products arel supplied thereto, as compared with the cracking conditions employed therein when unvaporized portions of the charging stock are cracked in this zone, either alone or in admixture with intermediate liquid products.` The temperature to which the gases are heated in zone 49 may range, for example, from 750 to 1200 F., or thereabouts, preferably-with a pressure in this zone substantially the same or somewhat higher than that employed in the vaporphase cracking step. The conditions employed in the polymerizing step will vary considerably depending upon the type of catalyst employed and upon the composition of the polymerization stock, both with respect to the relative proportions of paraflns and olefins in the stock and the particular type of olens present, as well as the relative proportions of the various types. In general, however, when the preferred solid phosphoric acid catalyst is employed,the temperature to which the polymerization stock is heated prior to its contact with the catalyst will range from 175 to 500 F., or thereabouts, with a superatmospheric pressure of from 100 to 700 pounds, or more, per square inch in the catalyst zone. The preferred catalyst referred to comprises a mix-` ture of the ortho and pyro-phosphoric acids on a relatively inert porous carrier such as kieselguhr. the catalyst particles being calcined prior to their use and a predetermined optimum degree of hydration being maintained in the catalyst bed during revivification of the catalyst to pre vent dehydration of the ortho to meta acid. 'For so-called selective polymerization (i. e., when the active ingredients of the polymerization stock consist essentially of butenes) pressures above 500 pounds-per square inch are preferred with temperatures of 'the order of 275 to 375 F. For

mixed polymerization (i. e.. when the active.

ingredients of the polymerization stock consists essentially of propene and butenes and substantial quantities of both are present) lower presmay be employed. When the active ingredients of thepolymerization stock consist essentially of butenes and pentenes, the ratio of iso to normal olenns is probablyv the most important factor in determining the optimum operating conditions,

but with such mixtures the optimum conditions will ordinarily be within the range vof the temperatures and pressures first above given.l Space velocities, as expressed in terms of the quantity 4of olenscontacted with a unit volume -of catalyst 'in a given time, must also be considered, but it is not the purpose of the invention to go into great detail on the subject of optimum polymerizing conditions since the many catalytic polymerization units now in commercial use have acquainted the industry withthe designed factors involved and the usual operating conditions which may generally be employed. The invention speeiiically contemplates the use of other well known catalysts, either liquid or solid, such as, for example, liquid phosphoric acids, sulphuric acid, aluminum chloride and the like.

As an example of one specific operation of the process, utilizing as charging stock a 28 A. P. I.

gravity Mid-Continent topped crude: the charging stock and selected low-boiling fractions ofl the intermediate liquid conversion products are sup\ plied to vaporizing and separating zone 3 wherein substantially all of their components which boil up to approximately 650 F. are vaporized by introducing highly heated gaseous products of the process into Vthis, zone. The admixed vapors and gases from zone 3 are subjected in Athe vapor` phase cracking step to an outlet temperature of Acracking step to an outlet temperature of approximately 930 F. at -a superatmospheric pressure of about 350'pounds per square inch. The total products of the mixed-phase and liquid phase cracking steps are commingled andl the resulting mixture is cooled to a temperature of approximately 670 F. by commingling regulated quantities of relatively cool intermediate liquid conversion products of the process therewith.

sures down to 300 pounds, or thereabouts, per

square inch may be utilized with good results andA Residual liquid` components are then separated from the'mixture and the remaining vapors are' fractionated to form relatively light and relatively heavy intermediate liquid products. Gasoline is condensed from the resulting fractionated vapors yand stabilized to a Reid vapor pressure of approximately 10 pounds per square inch. The l remaining normally gaseous fractions, including those evolved fromvthe gasoline by said stabilization, are separated into a relatively heavy fraction, consisting -predominantly of gases having 3 and 4 carbon atoms to the'molecule andcontaining a high percentage of propene andbutens, and a lighter fraction consisting" principally of gaseshaving 2 and less carbon atoms to the molecule. The relatively heavy fraction isfheated to a temperature of approximately 475 F. and then contacted with solid phosphoric acid catalysts at a superatmospheric pressure of approximately 450 pounds, per square inch. The temperature of the products leaving the catalyst zone f 100 pounds per square inch, the resulting heated products being introduced into separating zone 3 in sufcient quantities to vaporize the components of the charging stock and of the .intermediate liquid products supplied to this zone which boil up to approximately 650 F.

The above describedoperation will yield per barrel of ,charging stock, approximately 60% of `400 F. end point gasoline of high antiknock value, this product comprising a blend of the cracked and polymer gasoline produced. The remaining products of the process consist of residual liquid and that portion of the aforementioned relatively light gases not recycled to heating zone 49.

I claim as'my invention:

1. A hydrocarbon oil conversion process which comprises fractionating a mixture of cracked hydrocarbon vapors and gases to separate therefroma gasoline condensate, an intermediate fraction containing readily polymerizable gaseous oleflns and corresponding paraiins, and a lighter gaseous fraction, heating at least a portion of said lighter gaseous fraction to above the vaporizing temperature of the charging oil for the process, commingling with the charging oil, while the latter is below its vaporizing temperature, a suiiicient quantity of the heated gases to vaporize a substantial portion of the charging oil, cracking the resultant charging oil vapors while in admixture with the gases, separately cracking the unvaporized portion of the charging oil under mixed phase conditions, and supplying vaporous and gaseousv conversion products ofboth said cracking operations to the aforesaid fractionating step, additionally separating in said fractionating stepa relatively light and a relatively heavy reiiux condensate'and supplying the same,` respectively, to the vapor phase and mixed phase cracking operations.

2. A hydrocarbon oil conversion process which comprises fractonating a mixture of cracked hydrocarbon vapors and gases to separate therefrom a gasoline condensate and a lighter fraction containing polymerizable gaseous oleflns and corresponding paraiiins, subjecting said lighter fraction to polymerization to convert normally gaseous oleflns into liquid hydrocarbons, separating the latter from unpolyrnerized gases, heating at least a portion of the last-named gases to above the vaporizing temperature of the charg- .ing oil for the process, commingling with the charging oil, while the latter is below its vaporizing temperature, a sucient quantity of the heated gases to vaporize a substantial portion of the charging oil, cracking the resultant charging oil vapors while in admixture with the gases, separately cracking the unvaporized portion of the charging oil lunder mixed phase conditions, and supplying vaporous and gaseous conversion products of both said cracking operations to the aforesaid fractionating step, additionally separating in said fractionating step a relatively light and a relatively heavy reiiux condensate and supplying the same, respectively, to the vapor phase and mixed phase cracking operations.

3. A hydrocarbon oil conversion process which comprises ractionating a mixture of cracked hydrocarbon vapors and gases tokseparate therefrom a gasoline condensate, an intermediate fraction containing readily polymerizable gaseous olens and corresponding paraflins, and a lighter gaseous fraction, subjecting said intermediate fraction to polymerization to convert normally gaseous olens into liquid hydrocarbons, combining residual gases of the polymerizing step with at least a portion of said lighter gaseous fraction from the fractionating step, heating the commingled gases to above the vaporizing temperature of the charging oil for the process, commingling with the charging oil, while the latter is below its vaporizing temperature, a sufcient quantity of the heated gases to vaporize a substantial portion of the charging oil, cracking the resultant charging oil vapors while in admixture with the gases, separately cracking the unvaporized portion of. the charging oil under mixed phase conditions, and supplying vaporous and gaseous conversion products of both said cracking operations to the aforesaid fractionating step, additionally separating in said fractionating step a relatively light and a relatively heavy re-

Images