US2024996A - Conversion of hydrocarbon oils - Google Patents

Description

Dec, 17, 1,935. L. DE FLOREZ v CONVERSION OF HYDROCARBON OILS Filed July 1, 1953 BYU/6MM M ATTORNEY Patented Dec. 17,v 1935 UNITED STATES PATENT OFFICE i Luis de Fiom, rami-et, conn., assignor to The Texas Company, New York, N. Y., a corporation .0! Delaware Application July 1, 193s, serial No. 678,552

s claims.' (01.' 19e-4s) My invention relates to the pyrolytic conversion of hydrocarbon oils to oils of lower boiling point such as gasoline, and has for an object the provision of a process for converting hydrocarbon oil, such for example as crude petroleum or reduced crude, gas oil or the like, to nal products comprising gasoline, coke residue and, where desired, heavy fuel oil.

My invention has for further objects such improvenients and operative advantages and results as may hereinafter be found to obtain.

My invention relates more particularly to a method of treating hydrocarbon oils wherein a charging Oil is discharged into a distillation or dephlegxnation zone receiving hot cracked vapors produced' in the system. Dephlegmated vapors are withdrawn therefrom and fractionated to recover a gasoline distillate and a clean cycle stock. The cycle stock is heated to a. relatively highcracking temperature in a heating zone as for example by passing through a heating coil in a suitable furnace. Cracked products from the heating zone, together with oil to be coked, which may comprise charging stock, or a mixture of residue and condensate from the dephlegmation zone, are discharged into a cokingv zone wherein liquid constituents are retained under coking conditions toreduce the same to a coke residue, and the vapors from the coking zone are led into the dephlegmation zone to constitute the supply of hot cracked vapors thereto.

A system of this character is of considerable advantage in that it makes possible a combined cracking and coking operation in which the advantages of clean ciipulation may be obtained.

That is to say, the oil passed throughthe heating zone or cracking coil is of such a character as to enable it to be cracked under desirably high temperature and it may be in the vapor phase, and coking is accomplished largely by means of heat carried by the hot cracked products. In a system of this character, however, considerable excess heat may be available and it is to the better utilization of the excess heat and the consequent attainment of improved results that my invention is directed.

My invention contemplates, in a system of the general character recited hereinabove, by-passing a regulated 'portion of the hot cracked products from ythe heating zone around the coking zone and supplying them to the distillation or dephlegmation zone for the purpose of promoting cracking reactions therein, thereby improving the 55 yield` of light cracked distillate and effecting a y.better balance of conditions throughout the system.

My invention further contemplates the vselective treatment of separate charging stocks or separate portions of a suitable charging stock for the 5 purpose of producing bothv coke and heavy fuel oil, as well as light'cracked distillate.

In order that my invention may be clearly set forth and understood, I now prescribe, with reference to the drawing accompanying and forming 10 a part of this specification, various preferred forms and manners in which my invention may be practiced and utilized. In this drawing,

The single figure is.a more or less diagrammatic representation of a system for effecting the l5 conversion of hydrocarbon oils according to my present invention.

Referring now to the drawing, a charging stock, such for example as a crude or reduced crude, a, dirty vgas* oil or the like, is introduced 20 from a source (not shown) through a conduit I by means of a pump 2 into a primary dephlegmator 3 which receives hot cracked vapors from elsewhere in the system through conduits 4 and 5.

Contact between the charging stock introduced Z5 through the conduit I and the hot cracked vapors introduced through the conduits 4. and 5 within the dephlegmator 3 results in a combined distilling and dephlegmating action, higher boiling constituents of the vapors being condensed and 30 lower boiling constituents of the charging stock being volatilized. Moreover, due to the high temperature of the vapors entering the conduits 4 and 5 a. certain amount of cracking takes place, resulting in the accumulation in the bottom of 35 the dephlegmator 3 of a liquid comprising combined residual constituents ofthe charging stockand condensate from said vapors, which liquid fis withdrawn from the bottom of the dephlegmator 3 through a conduit 5.

The vapors reaching the top of the dephlegmator 3 pass through a vapor line 1 to a fractionating tower 8, the interior of which may provided with suitable plates or bubble trays 9, for the purpose of assisting in the fractionation.

By means of cool reflux oil introduced to the top of the fractionating tower 8 through a conduit II, or by means of cooling effected in any .other suitabley manner, the vapors entering the fractionating tower 8 are subjected to partial 50 condensation and fractionation for the recovery therefrom of higher boiling constituents comprisprising a clean cycle stock or gas oil which is withdrawn from the bottom of the fractionating tower through a conduit I2. Uncondensed 55 vapors reaching the top of the fractionating tower 8 are removed therefrom through a vapor line I3 and'passed to a condenser I4 wherein they are cooled to condense normally liquid constituents comprising light cracked distillate or gasoline. 'I'he mixture of condensate and uncondensed vapors passes through a line I5 to the gas separator I6 which is provided with a gas outlet I1 having a valve I8 and a condensate withdrawal line I9. 'Ihe gasoline condensate may be entirely removed from the system through a branch conduit 20 having a valve 2|, or aportion of this condensate may be withdrawn through a conduit 23 having a valve 24 and leading to a pump 25 which serves to return this portion of the condensate vthrough the reflux conduit II tothe fractionating tower 8. r

The gas oil or cycle stock withdrawn from the fractionating tower 8, which is of such character that it may be subjected to drastic cracking conditions without difficulty, is, as aforesaid, withdrawn from the fractionating tower 8 through a conduit I2 wherein is located a valve 21 and is delivered by means of a pump 28 and a conduit 29 to a heating coil 3| located within a suitable furnace 32.` While in transit through the/Heating coil 3|,l the gas oil or cycle stock is heated to a cracking temperature under conditions favoring a high degree of cracking per pass. I may employ a temperature of from 850 to 1050 F. and a suitable superatmospheric pressure of, for example, from 150 to 750 pounds per square inch. The resultant highly heated cracked products then pass through a transfer line 32 having a valve 33 into a coking drum 34. A portion, however, of the hot cracked products from the coil 3| are withdrawn through the conduit 5 to be by-passed around the coking drum 34 for introduction directly into the dephlegmator 3. lFor this purpose the conduit 5 is provided with a valve 35 and communicates with the transfer line 32 at a point between the coil 3| and the valve 33. By manipulating the valves'33 and 35 the relative proportions of hot crackd'products from the coil 3| delivered to the coking drum 34 and the dephlegmator 3, respectively, may be varied as desired.

Oil to be reduced to a coke residue is introduced into the coking drum 34 together with hot cracked products from the coil 3|. Such oil may be delivered directly to the coking drum 34 through a conduit 36 having valve 31 or may be introduced into the transfer line 32 through a conduit 38 having a valve 39, and may variously comprise a portion or all ofthe liquid withdrawn irom the bottom of the dephlegmator 3, a portion of the charging stock introduced through the conduit I or some other oil, suitable for coking.

- '42 and a pump 43 and communicating with the conduit 6 between a valve 44 located therein and the dephlegmator 3, as well as with the conduits 36 and 38. By manipulation of the'valves .42, 44,-

31 and 39 any desired portion or all of the liquid withdrawn from the bottom of the dephlegmator 3 may be delivered either directly to the coking drum 34 through the conduits-8, 4I and 36 or to the transfer line32 through the conduits 6, 4I and 38.

Alternatively, however, the valve 42 may be closed and all of the liquid Withdrawn from the bottom of the dephlegmator 3 may be removed from the system.

According to a, modified form of my invention ihe oil supplied to the coking drum 34 for coklng therein may comprise a second charging stock 5 which may dier in character from the charging stock introduced through the conduit I to the dephlegmator 3. In this instance, such a charging stock, for example, a, reduced crudeor a heavy residual oil resulting from a previous cracking 10 operation, may be withdrawn from a source (not shown) through a conduit 45 having a valve 46, to be delivered by means of a pump'41, the conduit 45, a conduit 48 having a 'valve 49 and the conduit 38, either to the transfer line 32 l5 or to the conduit 36 for delivery to the coking drum 34. f

In a still further modification of my invention, the stream of` charging stock, delivered/by the pump 2, through the conduit I, may be divided 20 into two streams, one flowing to the dephlegmator 3 and the other direct Jto the coking drum 34. For this purpose I provide a branch conduit 5| having a valve 52 which communicates with the conduit I at a point between a valve 53 located 25 therein and the pump 2, and with the conduit '48.

The liquid constituents are retained within the coking drum 34 where they are maintained at a coking temperature, preferably in excess of 830 F., lbeing thereby reduced to a coke residue which 30 may be removed from the coking drum 34 at the end of a run by means of the coke-boring apparatus provided for that purpose and indicated diagrammatically at 54. The evolved vapors are passed through the conduit 4 to the dephleg- 35 mator 3.

Pressures of, for example, 30 to 50 pounds per square inch, may be maintained in the coking maintained within the coking drum 34. l Prefer-v 50 l ably, however, the vapors are passed vthrough the coking drum 34, the dephlegmator 3 and the fractionating tower 8 with a minimum reduction of pressure.

Suitable baies 56 may be disposed within the 55 dephlegmator 3 for the purpose o1' promoting contact between the fresh charging stock and vapors therein and for the purpose of preventing residual .or dirty constituents from passing"y through the ,conduit 1 into the fractionaung 60' tower 8. Moreover, where desired, an additional light reiiux oil may be supplied to the upper portion of the dephlegmator 3, the apparatus for this purpose being readily comprehended by those skilled in the art, and, therefore, not illustrated in the drawing.

By means of the regulated by-passing of hot cracked products from the coil 3| around the coking drum 34 and the introduction of these highly heated products into the dephlegmator 3, crack- A ing reactions within the dephlegmator 3 are promoted, with the result that a high degree of conversion of the charging stock into desired liquid cracked distillate is made possible. At the same time any residual liquid returned from the delphlegmator 3 to the coking drum 34 is in such condition as to facilitate coking thereof. These results are accomplished by the utilization of excess heat in the hot cracked products leaving the coil 3l over and above that required for coking in the coking drum 34.

While I have hereinabove set forth and described various preferred procedures and conditions of operation by way of illustration of my invention, it will be understood by those skilled in the art that my invention is not limited t such illustrative examples but may variously be practiced and embodied within the scope of the claims hereinafter made.

I claim:

1. A combined cracking and coking process for converting hydrocarbon oil into products comprising a light distillate, heavy fuel oil and coke, which comprises subjecting a stream of oil while in transit through a heating coil to a cracking temperature, introducing a portion of said stream of cracked products from 4the heating coil into a coking chamber, directly admixing a residual oil to be coked from a source extraneous to the system with said portion of the stream being introduced into the coking chamber, retaining liquid constituents therein and maintaining them at a coking temperature to reduce them to a coke residue, passing evolved vapors from the coking chamber at a cracking temperature into a dephlegmating zone, introducing a stream of fresh charging stock into said dephlegmating zone and therein subjecting it to a cracking temperature by heat exchange with said vapors, introducing a further portion of the hot cracked products from said heating coil directly into said dephlegmating zone to promote the cracking of said fresh charging stock, withdrawing combined unvaporized charging stock and condensate from said dephlegmating zone and removing atleast a portion of this combined material from the system as a heavy fuel oil product, removing vapors from said dephlegmating zone and introducing them into a fractionating zone wherein they are fractionated to produce a condensate heavier than gasoline, withdrawing condensate from said fractionating zone and passing the same to said heating coil as charging stock therefor, removing vapors from said fractionating zone and condensing them to form the iinaljlight distillate.

2. A combined cracking and coking process for converting hydrocarbon oil into products comprising a light distillate, heavy fuel oil and coke. which comprises subjecting a stream of' oil while in transit through a heating coil to a cracking temperature, introducing a portion of the hot cracked products into a coking chamber, introducing a heavy oil to be coked from a source extraneous to the system into said coking chamber, retaining liquid constituents therein and maintaining vthem at a coking temperaure to reduce them to a coke residue, passing evolved vapors from the coking chamber at a cracking temperature into a dephlegmating zone, introducing a stream of fresh charging stock into said 5 dephlegmating zone and therein subjecting it to a cracking temperature by heat exchange with said vapors, introducing a further portion of the hot cracked products from said heating coil into said dephlegmating zone to promote the cracking of said fresh charging stock, withdrawing combined unvaporized charging stock and condensate from said dephlegmating zone and removing at least a portion of this combined material from the system as a heavy fuel oil product, removing vapors from said dephlegmating zone and introducing them into a' fractionating zone wherein they are fractionated to produce a condensate heavier than gasoline, withdrawing condensate from said fractionating zone and passing the same to said heating coil as charging stock therefor, removing vapors from said fractionating zone and condensing them to form the nal light distillate.

3. A combined cracking and coking process for converting hydrocarbon oil which comprises subjecting a stream of condensate oil While in transit through a heating coil to a cracking temperature, introducing a portion of the hot cracked products into a coking chamber, retaining liquid constituents therein and maintaining them at a coking temperature to reduce them to a coke residue, passing evolved vapors from the coking chamber at a cracking temperature into a dephlegmating zone, introducing a stream of fresh charging stock y into the system, passing a portion of said fresh charging stock into said coking zone wherein Athe liquid constituents thereof are retained and reduced to said coke residue, introducing another portion of said fresh charging stock into said 40 dephlegmating zoneand therein subjecting it tov cracking temperature by heat exchange with said vapors, introducing a further portion of the hot cracked products directly from said heating coil into said dephlegmating zone to promote cracking of said portion of fresh charging stock introduced into said dephlegmating zone, withdrawing unvaporized fresh charging stock from said dephlegmating zone and removing from the system at least a portion of the unvaporized stock thus withdrawn, removing vapors from said dephlegmating zone and introducing them into a fractionating zone wherein they are fractionated to produce a condensate heavier than gasoline, with-l drawing condensate from said fractionating zone and passing the same to said heating coil as charging stock therefor, removing vapors from said fractionating zone and condensing them to form a final light distillate.

LUIS DE FLonEz.

Images