US2366521A - Method of removing coke deposits from high-temperature oil lines - Google Patents

Description

Jgn. 2,` 1945.

J. J. GulcHE-r 2,366,521

METHOD OF REMOVING COKE DEPOSITS FROM HIGH-TEMPERATURE OIL LINES Filed Feb.' 25, 1943 i Patented Jan.2; 1945 METHOD on REMovING `corna; ffnerosrrs V`IFROM HIGH-TEMPERArURELoIL-IL'INES "JlulesLJ- G ilichetBatonRouge, La-, assigner Qto n Standard :Oil `Develop'l'nent Company, a c orpon n l I `ration of Delaware.` n

Appiioanon Ireblrluaryza 1943,;seria1iNo. 47790418 I f 3 Claims. Il. 1961-69) In This invention `relates toagmethod ofrmoving coke deposits from high-rtemperature oil lines and pertains lmoreparticularly to a method `of removing coke deposits l formed duringhigh--temtion within the separator. Unvaporized residue is removed from-the bottom of the separator I5 lthrougfhline II'I. I I; I

Vapors liberatedin the `separator I5 .compris- Y ing uvaporized Ioil Itogether I with an. substantial perature cracking of hydrocarbon roilsgforwthe 55 amount of steam are removed overheadfrom the production of `oleinic gases.` n `separator I,5througl1 line I8 and are; charged to `It has been the practicegto crack various oil alcracking coil-locatedin a furnace I9 in which n If'racgtions, such as .gas .oil,I Vkerosene 4andIlig-hter the -oil 'is rapidly heated to the desired reaction @il or hydrocarbon gases,`atV high temperatures, temperature. In cases where thecharging stock Suchas temperaturesfof the lorderlof from 1100" .Ello toithefheating coil I2 comprises a clean VaporizliO .l.400 F2, to produce ,oleiinic constituents, ableoil, theseparator l5 may bevomitted, orI the gsuchaslethylene, propylene, butadiene, and the products `from I`the heating 4coil I2 maybe bylikefWl-lichmayginfturn formstarting materials -passedthrough -line 2I directly to thecracking forftheIproduction of other products. 4Following coil I9. ,In the production of olenic gases as theIcrackingtreatment,it has been` the practice previously mentioned, the oil is subjected in the to-quench the cracked products below Iactive recracking coil III9 Ito temperatures of the order of @dion-temperature, suchasbelow 500l'. to 606 'n from1100 F.to 1400\-F., preferably between I F., `'prior Vtofsubjecting the cracked Amaterial to 1200 `and 1300\F. The oil is maintained fractionation and segregation. withinA the cracking coil I9 for a period suflcient ,It,1hasbeenfound thatwhen crackingoils in 20 to convertagsubstantial.portion thereofIinto-Iolethis manner, rocking diiculties `areencountei-'ed nic "gases, :such as ethylene, prop ylene, butyl- :the `I-egon Wherethe quenching liquidis inn enes andethelike.` l In Y n `z troducedintoItheoillstream.` 4fIhesejcoking ,dif- The cracked `products are yremoved fromIthe 4iulties-grequire frequent interruption of Ithe op cracking coil I9"thro`ugh Ia transfer line 22 into erationto remove the flcoke. I I "1125 which aquenching liquidsuch as an oilor water The principalobject ofIthepresent.invention` istintroducedflOm line 23. I n I is to "provide a `methodgof 1reducingfithe poking In accordance withythe present invention, this diiliculties just mentioned. I quenching liquid is first `introduced into the 'I'heabove and other objects of the invention (,g transfer Iline22 through line 24 at a point adja- .will beapparent'fromithe"y more detailedIdescrip- 50 cent the outlet nof thecrackingIcoil. The-introtion hereinafter-finwhioh reference will ,be made duction of the `quenching `liquid into :the hot, to the accompanying `drawing which is a diagaseous products removedfrorn the cracking..coil granuli.atcillustration` of equipment for high- I9 tends to form carbonaceous `deposits :in the I temperature cracking in which the present in region immediately adjacent the point of introvention nds particular application. 35 duction of the quenching liquid. The quenching Referring to the drawing, the reference charliquid is introduced through line 24 into the acter I0 designates a charge line through which transfer line 22 until a substantial amount of `the oil to be processed is introduced into the coke deposits is formed. The point of introducequipment. This `oil may comprise a crude petion of the quenching liduid is shifted from 5 troleum or a selected fraction thereonsuch as a `40 to 10 feet further downstream. As illustrated, gasoil, kerosene or, in some cases, hydrocarbon the quenching liquid passing through line 24 may gases. The oil introduced through line II) is be discontinued and the quenching liquid introcharged by means of pump I I to a vaporizing duced through branch line 25. The introduction furnace I2 in which the oil is heated to vaporize of the quenching liquid through line 25 into the a substantialportion thereof. High-temperature 45 transfer line is continued until the temperature I steam may be introduced through lineII3 at one at the original point of introduction of the or more spaced points within the vaporizing coil quenching liquid has been materially increased. to assistV the vaporization thereof. The oil after The increase in temperature at the point of inpassing through the vaporizing furnace I2 is troduction of the initial quenching oil through transferredthrough line I 4 to a separator II5 in 50 line 124 tends to expand the transfer line 22 and which vaporized constituents are separated from thereby loosen carbonaceous `deposits adhering unvaporized residue. Additional steam Imay be thereto. 'I'he carbonaceous deposits so loosened passed through line I6 into the bottomportion `are then carried out of thetransfer line 22 by of the separator to assist further in the vaporiza-` u the oil stream into a fractionating tower 26 from 21.

which they may be withdrawnthrough line After the carbonaceous deposits have been removed, the quenching liquid is again introduced through line 24. In other words, during the main portion of the operating period, the quenching procedure that the lengths of operating runs be- V tween shutdowns for removing coke deposits have in some cases been increased fivefold. vThis reduction in the number of shutdowns required for cleaning the equipment represents a material saving and increases the annual productive capacity ofthe cracking plant.

The cracked products after passing through the transfer line 22 discharge into a fractionating tower 26 wherein the products are subjected to fractionation to condense constituents boiling above the motor fuel boiling range. Condensate formed in the fractionating tower 26 is removed trom the bottom thereof through line 21. This condensate may be removed from the system through line 28, lor a part of it may be passed through line 29, cooler 3| and pump 32. and utilized as a quenching medium. Vapors remaining uncondensed in the fractionating tower 2B are removed overhead through line 33 to a condenser 34 in which the normally liquid constituents boiling in the motor fuel boiling range and steam are condensed. Products from the condenser 313 may be then passed tol a low-pressure product receiver 35 in which liquid distillate condensed in the condenser'34 is separated from the gaseous products. Steam distillate may be removed from the bottom of the low-pressure receiver 35 through line 36. Gaseous products separated from liquid distillate in product receiver 35 may be passed through line 31 to suitable equipment for separation of the olenic constituents therefrom. The liquid oil distillate separated from the water condensate and gaseous products in receiver 35 may be removed as a side stream through line 38.

Having described the preferred embodiment of 'the invention, it will 4be understood that it embraces such other variations and modifications as come within the spirit and' scope thereof.

What is desired to be protected by Letters Patent is:

1. In a process for the high-temperature conversion of hydrocarbon oils wherein a quenching medium is introduced into a stream of conversion products passing through a conduit following the conversion treatment and wherein solid deposits tend. to accumulate within the conduit in the region adjacent the point of introduction of said quenching medium; the method of removing said solid deposits which comprises introducing the quenching medium into the stream of conversion products at a predetermined point,` continuing the introduction `of said 'quenching medium at said point until a substantial amount of solid deposits is formed in the region adjacent said point of introduction, thereafter discontinuing the introduction of the quenching medium at said point,

introducing the quenching medium a substantial distance downstream from said rst-named point, continuing the introduction of the quenching medium downstream from said first-named point for a limited period only sufficient to increase the temperature of the conduit at saidrst-named point and loosen the solidiv deposits, and immediately thereafter again introducing the quenching medium at said first-named point.

2. In a process for cracking hydrocarbon oils to form olenic gases wherein the oil is subjected to cracking conditions of the ordery of from 1100" F. to 1400 F. and wherein a quenching medium is introduced into a stream` of cracked products passing through a conduit following. the

cracking treatment; the method of removing coke deposits formed at the point of introduction of .said quenching medium which comprises introducing the quenching medium into a stream of cracked products at a predetermined point, continuing` the introduction of the quenching medium at said point until a substantialA amount of solid deposits is formed in the region adjacent the point of introduction, thereafter shifting the point of introduction of the quenching medium a substantial distance downstream from said rstv. named point, continuing the introduction of the quenching medium at said last-named point for a limited period suflicient only toincrease the temperature of the'conduit adjacent the first-named point and to loosen solid deposits formed therein, and immediately thereafter returning the quenching medium to said first-named point.

3. Thev process dened in claim 2 wherein the quenching medium is a hydrocarbon oil.

JULES J. GUICHET.

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