US1784087A - Process and apparatus for the treatment of oil - Google Patents

Description

Dec. 9, 1930. BRANDT 1,784,087

PROCESS AND APPARATUS FOR THE TREATMENT OF OIL Original Filed Jan. 31, 1922 30 65 raw 74PM? Y 7 76 a? 8 5 8 r 74 84 l awn a4. sum/74c: CO/VJEA/SERS' .s'zzwn Cat 0544529)? 70 l0 a 6 .94

62 4, Z ZWn o/L 7g 14 16' ll afiWuw/mzvk 0510mm Au/v25 hydrocarbons therefrom, due to the forma- I gipe stills employed'in cracking operations.

; 30 interval; of time into an auxiliary chamber 40 the oil and, the subsequent cracking of the Patented Dec. '9, 1930 UNITED STATES" DAVID BRANDT, or wEs'rrmLD; NEW JEnsEY, ASSIGNOB r0 Dom rY RESEARCH.

\ COMPANY, or new YORK, n. z, A CORPORATION or DELAWARE PATENT OFFICE rnocnss AND APrAaA'rus-ron THE maximum or 01 Application filed January 31, 1922, Serial 110. 532,954. lama m 11 .1928.

This invention relates to a process of and apparatus for the treatment of oil, and more particularly to a process and apparatus for cracking hydrocarbon oils to produce gaso- 5 line and other lighter hydrocarbon oils therefrom.

Heretofore considerable difiiculty has been experienced in the treatment of the higher boiling hydrocarbons to produce low boiling tion of coke or carbon-deposits on the heat transferring surfaces of the apparatus employed, such as on the walls of the stills and on the interior of the pipes of the common uch deposition of carbon'results in alowering of the heat conductivity of the heat transferring surfaces, and, moreover, frequently results in a burning of the metal or in a rupture of the still emplo ed,

The primary object o the present inVen-* tion is to provide a process of and an apparatus for cracking oil which will overcome the deposition of coke or carbon on the heat transferring surfaces of the apparatus in which oil is treated.

In accordance with this object, one feature of the invention contemplates passing the oil from the still in which it is heated for a short in which no heat is applied, but in which the. oil isallowed to remain for a sutlicient length of time to produce cracking thereof. The carbonaceous material which is formed in this chamber is removed and the oil is recirculated "to the still to be further heated.

The circulation of oil through a comparatively small pipe in a pipe still in order to eiiiciently and uniformly heat and vaporize o1 virr a'fc'racking chamber requires the handling and circulation of a ver high temperature oil. Due to mechanical hmitations it has not been possible up t6 the present time'to secure i a pump which will handle the oil at the high temperatures which"' a're necessary for .oil cracking. A

' Accordingly, another object of the invention is to provide a process of and an appa- -rat us for cracking oil by which the oil may be .the boiling points of the oils general practice.

, heated and vaporized in a pipe still, and

cracked in; an au'xilia chamber while mainof the oil. 7 With this object in view, another feature of the invention contemplates the connection of a heating still and cracking chamber in ,such a manner that a positive and active circulation may be maintained propeller'that will not be affected by the high by means of a temperature oil.

With these and other objects in view, the

invention consists in the improved processand apparatus of cracking oil hereinafter described and claimed.

The present invention is supported by the 1 following theoretical considerations:

It is well-known that the crackin of hydrocarbon oils to produce lower boi ing oils therefrom depends upon a time reaction, the velocity of which varies with the temperature and the pressure to which the oil is subjected.

In order to attain the necessary temperature for treating the oil it is generally necessary to \heat the oil under a super-atmospheric pressure for the reason that the boiling polnts ofthe oils under atmos heric pressure are as e cracking temperaoil to pressure are raised in known laws. It has been the to crack oils by heating the a general rule below t tures. By thus subjecting the conformity with same in contact face until cracking to the desired extent has taken .place, and thereafter passing the vapors through undesired heavier portions of the treated oil,

and then permitting the vapors to pass to a condenser to obtain thedesired lighter frac-- tions. It has now been found that an 011 may be rapidly heated to -a crackingtemperature in a heated zone while vaporlzation of the oil proceeds without efiectlng any appreciable cracking during the short'1nter-- val of time to which it is subjected to the heat treatment. If it be then withdrawn at once to a heat insulated zone and maintained at the cracking temperature for a sufliclent length of time, the desiredcrackin Wlll take place and the carbonaceous material formed a dephlegmator to remove the with the highly heated surin the reaction will be deposited in this zone instead of in the heating apparatus and the dif'liculties due to deposition of carbon on the heat transferring surfaces will therefore be avoided.

The various features of the invention are illustrated in the accompanying drawings, in which,

Fig. 1 is a diagrammatic view in side elevation of the apparatus, parts of which are shown in section; and

Fig. 2 is a view in elevation of the heating still, parts of which are shown in section.

Oil to be treated such as fuel oil, gas oil, kerosene, or crude oil, is pumped through a pipe 2 to a pipe 6 by means of a pump 4, and is then passed through a series of surface condensers 8 in which the oil is heated by vapors passing through the condensers in a direction countercurrent to that of the oil being fed to the apparatus. In passing through the condensers 8 the incoming oil is heated to a temperature of approximately 400 to 450 F. From the condensers the oil passes through a pipe 10 into a dephlegmator 11, which is preferably maintained under a pressure in the neighborhood of 100 pounds. The oil from the pipe 10 flows into a tray 14 and flows over the serrated edges or saw teeth thereof to a baffle plate 16, which has a central opening therethrough, the edges of which are serrated in the same manner as the tray edges above described. The oil passes through the central opening of plate 16 and through a series of trays and battles similar to 14 and 16. As the oil overflows the trays and plates it forms a thin sheet or spray of liquid and meets a current of ascending vapor which is at a higher temperature than the descending liquid and serves to vaporize the lower boiling distillate therefrom. The ascending vapor is cooled by the descending liquid and the higher boiling fractions of the vapor thereby become condensed and separated from the vapor, due to the washing action of the liquid.

From the dephlegmator 11 the oil passes through a central opening of the lowest plate in the series into a cracking-chamber l2,

maintained at the same pressure as the dephlegmator. and in which there is 1nain tamed a column of oil undergoing the cracking treatment. As the mixture of incoming and residual oil passes downwardly through the cracking chamber 12 a portion of it is cracked and another portion is vaporized. The vapors produced pass upwardly through the oil and then through the dcphleg mator 11. The oil reaching the bottom of the chamber overflows through an outlet pipe 18 by which it is conducted to a lower drum 20 of a cracking still 22. From the drum 20 the oil is passed through a series of small tubes 24 to a vapor separating drum 26. The tubes 24 are located within a heating furnace 28 and come into direct contact with the combustion gases. The circulation in the tubes is comparatively fast to prevent the accmnulation of carbon therein, and although the heat transmitted to the oil, and the pressure thereon is sufficient to raise the oil to a cracking temperature, there is Very little cracking which takes place during the time interval during which the oil is passing thercthrough, but a large amount of oil is vaporized in the tubes. The vapors formed in the heating still 22 are separated from the oil in the drum 26 wherein a substantially fixed level of oil is maintained. To accomplish this separation a dome 30 is mounted on the drum 26 and a vapor pipe 32 connected with the dome is provided with a valve 34 by which a pressure may be maintained on the oil to hold the oil level at any desired point. The oil flowing through the drum 26 passes into a separator 36, which is provided with a pocket to collect carbon and heavy residues, and the oil is led from the separator through a pipe 38 to the upper portion of the cracking chamber 12. The vapors passing through the pipe 32 are introduced into the lower portion of the cracking chamber 12 and are given a circuitous path through the oil by means of a series of bafiles 40 and trays 42 in passing to the upper portion of the cracking chamber. Depending from the bottom of the baflles 40 and the trays 42 are a series of aprons 44 which have serrations to cause the gas to have an extended path of travel through the oil. Said depending aprons 44 also provide a series of pockets beneath the battles 40 and trays 42 within which gas and vapors accumulate under pressure of descending oil thus providing in the aggregate a large free surface of oil from which the vapors may disengage themselves from the descending oil column. As the oil is cracked and the lighter cracked constituents released therefrom its density increases and carbon and tarry matter are deposited from the oil. This carbon and tarry matter works downwardly through the still around the ballies and trays aml accumulates in a collecting chamber in the bottom of the cracking chamber. To prevent. the tarry and carbonaceous matter from being circulated through the heating still, the inlet of the pipe 18 is positioned a considerable distance above the bottom of the cracking chamber, and a cap 43 is placed over the inlet to prevent the carbonaceous material from being. drawn directly into the pipe. Any heavy material which collects in the heating still drum 20 may be withdrawn through a draw-off pipe 45.

Practically all of the cracking of the oil is accomplished within the heat insulated chamber 12 by the countercurrent circulation of the oil and vapors. As the hot vapors pass through the oil, portions of the vapors are broken down and a portion of the oil is cracked. All vapors which are set free pass upwardl throu tween the oil and vapors. The oil gldthe oil and are in turn intimate y scrub and treated by the'hot oil. One of the main functions therefore of the arrangements shown in the drawings is to obtain the countercurrent circulation bethe oil within pipe 38 has been deprived of its lighter fractions, the oil column on the outside of the pipe hasa lower specific gravity. To insure that the vapor and oil will be separated in drum 26 in order to secure the countercurrent scrubbing between the oil and vapors in chamber 12, it is necessary that the liquid level in the drum 26 be maintained substantially along the dotted line 2525 shown in Flg. 1, which level is indicated by a gauge glass 46 maintained at theend of the drum, and that the oil level in the chamber 12 shall be -substantially along-the dotted line 13--13 shown in Fig. 1. A propeller 47 is placed within the tube 18 whichsets up an activelcirculation of the oil to give a comparatively high velocity of flowaof oil in the tubes 22 and to act further to overcome the gravity head of the oil in the chamber '12 and the frictional resistance of the liquid circulation in the apparatus. The propeller 47 is mounted upon a rod which passes through a packing gland 49 in the pipe 18 so that this construction does not require the packing and sealing which is necessary in using a recipro-.

eating or rotary pump for handling hot oil.

In order to prevent an excessive accumulation of coke or tarry matter in the bottom of the cracking chamber 12, a pipe '48 is provided, having a valve 50, through which coke or' tarry matter may be Withdrawn at intervals, and passed into a coke trap or separator 52. In the same way the" tar or coke which-has separated from the oil in passing through the drum 26 and settled into the .separator 36, may be Withdrawn through a pipe 54 by opening the valve 56 therein. In-

the passage of the coke and tarry matter-to the separator 52, a considerable amount of oil, which is associated therewith passes into the separator, which it is desirable to recover to prevent excessive loss of oil." One means which may be employed for this purpose is to=1nake use of thesensible heat of the oil to accomplish its distillation, by gradually releasing the pressure thereon, and allowing the vapors to pass out of the separator into a condenser. A vapor pipe 58 connected to theupper end of the separator leads to a condenser 60, and is provided with a valve 62 which may be gradually opened after closing valves and 56 in pipes I48 and 54, to permit vapors to pass to the coiidenserl The assing closed during distillation to prevent a reduc tion in pressure in other parts of the apparatus. .After separating thevolatile portion of the material in the tarseparator, a valve 64in a residuepipe 66 is opened to ermit the residue to be runoff. If desired, lnstead of allowing the. volatile portion of valves 50 and 56 in pipes 48 and 54 must be v the material inthe tarseparatorq52 to. pass to a condenser, the whole mass maybe drawn off through pipe 66 andpjassedthrough a filter to remove the carbon, and thetoil may then be utilized in any manner desired.

After the vapors have been scrubbed in. the I oil in the crackingchamber 12 they pass up-'v Wardly. through the dephlegmator 11 where the vapors of the high boiling pointoils are condensed in the oil introduced into the dephlegmator and carried back into the cracking chamber. vThe remainder of. the higher boiling pointv fractions in the vapors are removed in a steam condenser .68 which is mounted immediately above the de phlegmator 11 and in direct communication, therewith. The condenser 68 comprisesacylin-v drical body having tubes 70 connected be-v tween tube sheets 72 and 74, and a series of.

telescopic tubes, 76 arranged to be adjusted in the tubes 70 by means of a screw 78 and motor 80. The structural details of the condenser 68 are not claimed or completely illustrated herein, but are fully disclosed and claimed in my copending application Serial No. 532,955, filed of even date herewith which has matured into Patent 1,613,016. Water is admitted into the condenser through a pipe 82 and the steam generated around the tubes is withdrawn through an outlet 84.

After the high boiling point fractions have been taken out of the vapors in the condenser 68, the remaining vapors pass through a line 86 into the first of a series of the fractional condensers 8. The. vapor fractions separated in the condensers 8 are separately collected and the uncondensed vapors pass out of the last condenser through a pipe 88 and flow through a condensing coil 90 positioned in a condensing box 92. The lowest boiling point vapor fractions are condensed in the coil 90 and pass into a separator 94 where uncondensed gas is separated and led off through a pipe 96, and the condensate is removed through a pipe 98.

With the process outlined above the oil introduced into the apparatus is gradually raised to the cracking temperature, and any low boiling point vapors are removed from the oil and forwarded to a fractional condenser befo e the oil reaches the cracking chamber. he oil is gradually cracked as it passes downwardly through the cracking chamber 12 and any oil .which is not vaporized or cracked is circulated front the cracking chamber through the heating still to be vaporized and superheated, to assist in cracking the oil flowing into the cracking chamber. In this way the oil iscirculated in a closed cycle from the cracking 'chamber through the pipe heating still and returned, and the oil gradually cracked until its gravity is so increased that it is not desirable to again circulate it through the highly heated cracking still 22. To avoid carrying the heavy residuum into the pipe still the gravity of the oil in the cracking chamber 12 is closely inspected and when it increases to such a point that there is likelihood of the formation of carbon in the tubes 24, the residuum together with a comparatively large amount of oil is withdrawn through the outlet 48 into the carbon separator 52. Also, the withdrawal of the heavy residuum from the separator 36 assists in maintaining an oil body which may be continuously cracked without the likelihood of an excess formation of carbon.

The arrangement of the cracking chamber and the pipe heating still is such that gravity will assist in carrying on the circulation and therefore it is not necessary to use a reciprocating or positively acting pump in maintaining the oil circulation. This construction provides an important advantage from an operating standpoint because the initial cost and the cost of operation of the hot oil pumps is very high.

Having thus described the preferred form of the invention, what is claimed as new is:

1. In an apparatus of the kind described a pipe still having a lower and upper drum and a series of pipes connecting the same, means for heating said pipe still, a cracking chamber, conducting means connecting the lower portion of the cracking chamber with the lower drum of the still, oil conducting means connecting the upper drum of the said still with the said cracking chamber, a separate vapor connection between the upper drum and the cracking chamber, means located in the conducting means connected tothe lower drum of the still for forcing oil to be treated into the said lower drum to cause circulation between the cracking chamber and the still, means for withdrawing vapors from the said cracking chamber and condensing the same.

2. In an apparatus of the kind described a set of relatively small tubes, means for. heating the said tubes, a cracking chamber, tubular means for conducting oil from said cracking chamber to said tubes, a propelling means within said tubular means, a vapor separator connected to said tubes, a vapor pipe connecting the vapor separator with the lower portion of the cracking chamber, a conduit for conducting oil from said vapor separator to the upper portion of said cracking chamber, means for feeding oil to the liquid circuit of which said cracking chamber is a part and which also includes said tubular means, said small tubes, said separator and said conduit, means for withdrawlng vapors from the sand cracking chamber and means for condensing said vapors.

3. In an apparatus of the kind described.

ing chamber, conducting means connecting the lower portion of the cracking chamber with the lower drum of the still, conducting means connecting the upper drum of the still with the said cracking chamber, a vapor dome connected to the upper drum of the still, a vapor pipe connecting the said vapor dome with the cracking chamber so as to cause contact between the vapor and the oil in the said cracking chamber, means for causing a circulation of oil between the said cracking chamber and still, a tar separator, means for withdrawing tarry matter from the lower portion of the said cracking chamber and conducting the same to the said tar separator, means for withdrawing tarry matter from the upper drum of the still and conducting the same to the said tar separator, means for Withdrawing the lighter hydrocarbons from the tarry matter passed to the said tar separator and means for condensing the same, means for withdrawing the residue remaining after the separation of the lighter hydrocarbons, means for withdrawing vapor from the said cracking chamber, means for feeding oil to the said cracking chamber in heat transferring relation to the vapors being withdrawn and means for condensing the said Vapors.

4. A process of producing low boiling point hydrocarbons from high boiling point hydrocarbons which comprises maintaining a body of high boiling point hydrocarbons at relatively high temperature, passing oil from said body by direct open comn'lunication to a heating Zone, breaking the oil up into a series of fine streams as it passes through said zone, maintaining a superatmospheric pressure on the said oil and heating the oil to a sufficiently high temperature to vaporize a substantial portion thereof, separating the oil and vapor issuing from said heating zone, introducing the separated oil into-said oil body by a second direct open communication, introducing the separated vapors into said body of oil at a level below the delivery of said second open communication and propelling the oil while passing th rough said first open communication between the oil body and the heaterv to impart velocity thereto and to-maintain a flow of liquid in said oil body contrary to the direction of flow of vapors therethrough.

5. The process of producing low boiling point hydrocarbrms from high boiling point hydrocarbon oils, which comprises maintaining a body of oil in a cracking zone. passing oil from said zone through a heating zone at a relatively high velocity whereby a porllit passing the unvaporized portion of the high- ,ly heated oil directly into a cracking zone where the oil remains in its highly heated state a suflicient length (iftime to permit the cracking of said high boiling. hydrocarbons whereby low boiling hydrocarbons are produced, separately withdrawing said vaporized hydrocarbons from said heating zone and passing them into the said heated oil in said cracking zone, withdrawing the said low boiling hydrocarbons in the form of vapors from the cracking zone and fractionally'condensin the same.

i. The process of distilling oil, which comprises passing oil at a relatively high velocity through a heating zone to heat the oil to a ing means,

cracking temperature and vaporize a portion thereof, passing the unvaporized portion of the heated oil at a relatively low velocity from said heating zone directly into a cracking zone, yigorously agitating and heating oil in said cracking zone by separately passing the highly heated vapors. from the heating zone through and in direct contact with the oil inthe cracking zone.

8. In an apparatus for cracking hydrocarbon oils, a cracking chamber of relatively greater vertical than horizontal dimensions,

means for malntaining a body of oil in said chamber, oil heating means adjacent said chamber, means for passing oil from the lower portion of said chamber into said heatmeans for returning unvaporized oil from said heating means directly into the upper portion of said chamber and independent means for passing vapors from sa d heating means into the body of ml in said chamber at a point in the lower portion thereof. g

9. A method of cracking hydrocarbon oils, which comprises circulating the oil from and to a bulk supply tank through a heater maintaining a large body of oil in the bulk supply tank,-heating the oil to a cracking temperature in the heater, causing a stratification of the oil in the bulk supply tank by obstructing the free flow of oil downwardly in said body and thereby confining the turbulence due to the introduction of; the oil from the heater into the bulk supply tank to the upper stratum, and withdrawing oil from the lower stratum for recirculation through the heater.

10. Amethod of cracking hydrocarbon oils, which comprises mechanically circulating the oil from and to a bulk supply tank through a heater maintaining a large body of oil in the bulk supply tank, heating the oil to a cracking temperature in the heater, causing a stratification of the oil in the bulk sup-.

ply tank by obstructing the free flow of oil downwardly in said body and thereby confining the turbulence due to the introduction of the oil from the heater into the bulk supply tank to the upper stratum, and withdrawing oil from the lower stratum for recirculation through the heater.

11. A method of cracking oils, which comprises circulating the oil from and to a bulk supply tank through a heater maintaining a large body of oil in the bulk supply tank, heating the oil to a cracking temperature in the heater, causing a stratification of the oil in the bulk supply tank by obstructing the free flow of oil downwardly in said bodyand thereby confining the turbulence due tothe introduction of the oil from the heater into the bulk supply tank to the upper stratum, subjecting the vapors escaping from the bulk supply tank to a refluxing operation, returning reflux to the oil in the bulk supply tank, and withdrawing oil from the lower stratum for recirculation through the heater.

12. A method of cracking hydrocarbon oils, which comprises circulating the oil from and to a bulk supply tank through a heater main taining a large body of oil in the bulk supply tank, heating the oil to a cracking temperature in the heater, causing a Stratification of the oil in the bulk supply tank by obstructing the free flow of oildownwardly in said body and "thereby confining the turbulence due to the,introduction of the oil from the heater into the bulk supply tank to the upper stratum, subjecting the vapors escap- 4 2 hydrocarbon 0 withdrawing from the lower stratum the oil circulated through said heater.

1 3. A method of cracking hydrocarbon oils, whlch comprises circulating the oil from and to a bulk supply tank through a heater maintaming a large body of oil in the bulk supply tank, heating the oil to a cracking'temperature in the heater, causing a Stratification of the oil in the bulk supply tank by obstructing the free flow of oil downwardly in said body and thereby confining the turbulence due to the introduction of the oil from the heater into the bulk supply tank to the upper stratum, withdrawing tar from the lower stratum, and recirculating oil withdrawn from the lower stratum through the heater.

14. A method of cracking hydrocarbon oils,

which com prises circulating the oil from and to a bulk supply tank through a heater maintaining a large body of oil in the bulk supply tank, heating the oil to a cracking temperature in the heater, causing a Stratification of the oil in the bulk supply tank by obstructing the flow of oil downwardly in said body and thereby confining turbulence due to the introduction of oil from the heater into the bulk supply tank to the upper stratum while permitting circulation of the unvaporized constituents to-the lower stratum, and withdrawing oil from the lower stratum for recirculation through the heater.

15. A method of cracking hydrocarbon oils. which comprises circulating the oil from and to a bulk supply tank through a heater main taining a large body of oil in the bulk supply tank, heating the oil to a cracking tempera ture in the heater, causing stratification of the oil in the bulk supply tank by obstructing the free flow of oil downwardly in said body and thereby confining turbulence due to the introduction of oil from the heater into the bulk supply tank to the upper stratum while permitting circulation of unvaporized oil and associated tarry constituents to the lower stratum, withdrawing tar from the lower stratum, and recirculating oil withdrawn from the lower stratum through the heater.

10. A method of cracking hydrocarbon oils, which comprises circulating the oil from and to a bulk supply tank through a heater maintaining a larger body of oil in the bulk supply tank, ture in the heater, causing a stratification of oil in the bulk supply tank by obstructing the free flow of oil downwardly in said body and thereby confining the turbulence due to the introduction of the oil from the heater into the bulk supply tank to the upper stratum, withdrawing oil from the lower stratum for recirculation through the heater, and with drawing tar from the operation from the lower stratum and supplying fresh charging stock.

17. An apparatus for distilling hydrocarbon oils under pressure, comprising a bulk supply tank and a heater, circulating connections from the lower part of the bulk supply tank to the heater and from the heater to a higher part of the bulk supply tank, and battle means for confining turbulence to the upper stratum of oil in the bulk supply tank arranged in the bulk supplytank between the circulating connections from the heater and the circulating connections to the heater below the normal liquid level therein.

18. An apparatus for distilling hydrocarbon oils under pressure, comprising a bulk supply tank and a heater, circulating connections from the lower part of the bulk supply tank to the heater and from the heater to a higher part of the bulk supply tank, bafiie means for confining turbulence to the upper heating the oil to a cracking temperastratum of oil in the bulk supply tank arranged in the bulk supply tank between the circulating connections from the heater and the circulating connections to the heater below the normal liquid level therein, and a connection for withdrawing tar from the bulk supply tank below said battle means.

19. An apparatus for distilling hydrocarbon oils under pressure, comprising a bulk supply tank and a heater, circulating connections from the lower part of the bulk supply tank to the heater and from the heater to a higher part of the bulk supply tank, and means arranged in the bulk supply tank between the circulating connection from the heater and the circulating connections to the heater below the normal liquid level therein for causing a stratification of oil in the bulk supply tank and for confining turbulence to the upper part of the bulk supply tank.

n apparatus for distilling hydrocarbon oils under pressure, comprising a bulk supply tank and a heater, circulating connections from the lower part of the bulk supply tank to the heater and from the heater to a higher part of the bulk supply tank, and means arranged in the bulk supply tank between the circulating connections from the heater and the circulating connections to the heater below the normal liquid level therein for preventing turbulence in the lower part of the bulk supply tank.

In testimony whereof I aflix my signature.

DAVID G. BRANDT.

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