US1901592A - Method for heating oil - Google Patents

Description

March 14, 1933. A. E. HARNsBERGn-:R ET Al. 1,901,592

METHOD FOR HEATING OIL,

Filed Jan. 29, 1929 I do: wmf

Patented Mar. 14, 1933 UNITED. STATESV PATENT' oniricav A'UDLEY E. HABNSBERGER AND CLYDE L. SMITH, OF CHICAGO, ILLINOIS, ASSIGNORS T0 GYRO PROCESS COMPANY, OF DETROIT, MICHIGAN, 'AYCORPORATION OF-MICT IGAN METHOD FOR HEATING o-IL Application led January 29, 1929. Serial No. 335,834.

In the cracking of oil in the vapor phase it is customary to subject the oil first to temperatures sufficiently high to vaporize the oil but without substantially cracking the same.. The oil which remains in liquid form after being thus initially heated is removed from the system while the vaporized frac-l tions thereof are separately passed into 'a high temperature or converting zone wherein said oil vapors are brought to cracking temperatures and the conversion reactions are permitted to continue for a desired period of time. It has been found in the operation of these systems that the vapors entering the cracking or high temperature zone of the heating apparatus contain an appreciable amount of oil in liquid form, due, possibly, to entrainment. This liquid oil'in the con; verting zone vris highly undesirable for the reason that it collects on the highly heated walls of the tubes used in the cracking zone and produces a coke or carbon deposit which interferes seriously with heat transfer,-blocks the free passage of oil vapors through the tubes andl interferes inkmany other respects with the sustained or continuedoperation of commercial systems of thischaracter. p

It is therefore important to ldeprive oil vapors of all liquid entrainment before such vapors are admitted `into the high tempera?V ture cracking tubes, and it is to this end thatthe present inventionv is specifically directed.

It is therefore an outstanding object of the invention to provide an oil heater for cracking o`il in the vapor phase wherein the heater is formed to include a setting divided by a transverse bridge wall into burner and tube compartments, the tube lcompartmentbeing provided with a seriesof tubes through which the oil vapors travel while being subjected to the decomposition temperatures prevailing in the heater and wherein the furnace gases after passing over said tubes, but

before leaving the settingand at relatively L low temperatures, are brought into contact witha plurality of relatively enlarged tubes constituting what is known as a preheating or drying'section, whereby the waste heat of the furnace is utilized for heating the oil and oil vapor passing through said preheatingi bank to Vaporize the liquid content thereof before said vapors are admitted into the cracking tubes of the' appara-tus.

For a further understanding of the invention reference is to be had to the followling description and to the accompanying drawing wherein:

Figure l is a diagrammatic View, partly in vertical section, of the apparatus employed in carrying out the present invention,

Figure 2 is a transverse sectional view on the line 2 2 of Figure l.

Figure 3 is a view showing a slightly modified form.

-Referring more particularly to the drawt 'l ing, the numeral l designates an oil furnace Y ror converter which is formed to comprise a setting 2 provided internally with vavertical transversely extending bridge wall 3,- which divides the interior of the converter intoburner and tube compartments 4 and 5 respectively. The burner compartment is provided with oil burners or other combustion-devices 6 and these furnace gases'pass ,upwardly toward the roof 7 of the converter and vthen sweep downwardly through the tube-'compartment 5, finding exit frein theV 1converter by way of the stack or`other outet.8; y

fArranged within the converter are longi tudinally extending rows or passes of cracking tubes 9. k,The upper pass, indicated by l.the characters 9a, pass over the burner compartment 4, restsfon the top of the bridge wall 3 and also'yextends over the tubeco'mf partment 5. This passof tubes has its foirward' end connected with a header 10, while the rear ends of the upper pass of tubes are connected by return bends, or other suitable means, with the lower passof tubes 9,- the converted vapors leaving the outlet ends of the tubes 9 being passed linto-cooling and fractionating apparatus 11. v l' Arranged in the tube compartment 5 below the tubes 9 is a bank of preheating or drying tubes 12. These tubes extend substantially at right angles to the tubes 9 and are l of materially greater diameter. For example, the tubes lK9 may possess an outside diameter of three inches, whereas the tubes 12 possess,

for example, an outside diameter of six inches or more. The tubes 12 are located in the relatively cooler portions of the converter. Thus the temperature in the burner compartment may be as high as 2200 F., the temperature in the upper portion of the tube compartment 1800 F., the temperature around the preheating tubes 12 1300 F., and

the outlet temperature substantially 1200 F.

In carrying out the system oil is first passed through a tube still or vaporizer 13.where it is brought to a temperature of approximately 700 F. This temperature is sufficiently high to vaporize the. desirable fractions of the oil but not to materially crack the same. The

oil leaves the vaporizer 13 and passes, into an evaporator 14, which serves to separate the vaporized fractions of the oil from the liquid fractions, the latter being discharged from the bottom of the evaporator as fuel oil. From the evaporator the vapors pass by way `of a pipe line 15, in which is arranged a liquid trap' 16 to the inlet side of the ,preheating tubes 12,-and enter said tubes at a temperature ofroughly, 600 F. Thevapors are then passed through the tubes 12 and subjected to the temperatures prevailing in the outlet side of the converter. Due to the relatively large diameter of the tubes comprising the bank 12 and the fact that these tubes are lo ated in the outlet portion of the converter,

- the oil vapors passing through the tubes 12 are dried or preheated to remove therefrom all liquid lentrainment, with the result that when said vapors are discharged from the tubes 12 and pass by way of a pipe line 17 of thetubes 9. By reason of their relatively to the header 10 they are in a substantially dry state whenl introduced into the inlet pass large internal area the tubes 12 may be readily cleaned from time to time of such carbon from 80 to 100 degrees, and. this temperature or coke deposit which may accumulate therein; The tubes `comprising the bank 12 are preferably connected so that the vapors pass' therethrough serially, since this tends to produce high velocity and good heat transfer.

Thel temperature rise in the vapors while passing lthrough the' drying tubes varies is sufficient to thoroughly dry the vapors but not suiiiciently high to overheat or appreciably crack the same. For example, the outlet vtemperature ofy the vapors when leaving the a .tubes 12 may be approximately 700 F.'

. In the present invention the coke which forms as a result of the drying will not choke the tubes that are arranged in`parallel order, which is the arrangement in the bank 9. The

presence of coke, for example, in the entrance portion of the tubes 9a is extremely detrimental due tothe very high temperatures at the inlet and which if present is apt to result in the burning out and mechanical failure of the tubes. Coke on the interior of the preheater-or drier 12, will not in any Vway be damaging since the furnace` temperature at this ypoint is in the neighborhood of 1200 T The tubes 12 can, therefore,

operate with small amounts of coke in them' for a period rof time without danger of burning out because of the low temperatures employed. One of the outstanding features of `this invention is that of introducing dry or slightly super-heated oil vapors into a cracking zoneror tube. t

7e prefer for reasons of economy to situate the preheating or drying tubes in the converter setting. It is obviously within the scope of the invention, however, to place these tubes ina separately heated element, as disclosed in Figure 3, the element being indicated by the numeral 18 and is arranged as a part of the pipe line leading from the evaporator 14 to the tubes`9.

What is claimed is.:

1. The method of cracking oil in the vapor phase, which consists in heating a continuously moving elongated stream of oil of re-.

stricted cross-sectional area tofa temperature y at which portions thereof will vaporize without molecular decomposition, passing the heated oil to an enlarged zone and therein separating said vaporized product from the portions which do not vaporize without moi lecular decomposition, then passing said vapors through an intermediateheating Zone in Yan elongated stream of restricted` cross-secpassing a moving stream of such oil-through a primary heating zone and therein heating the oil to a temperature at which portions thereof will vaporize without molecular decomposition, substantially separating such vaporsin an externally unheated zone from' the remaining portions of the oilwhich do not vaporize without molecular decomposition, passing said vapors in a confined moving stream through an intermediate heating zone possessing a-higher temperature than said primary zone to effect vaporization of the entrainedunvaporlzed oil present 1n said vapors as a'mist or suspensoid to reduce said vapors to a substantially dry moisture-free state without permitting any appreciable cracking thereof to take place, then passing said dry vapors in a confined moving stream at a velocity materially greater than the velocity of the vapors in the intermediate zone through an elongated 'cracking zone of restricted cross-sectional area wherein said vapors attain a cracking temperature in excess of 10000 F., and utilizing the same products of combustion which are employed to heat the cracking zone to a high temperature for heating the intermediate drying zone to a lower temperature.

3. The method of cracking hydrocarbon oil in the vapor phase, which consists in passing a moving stream of such oil through a primary heating zone and therein heating the oil to a temperature at which portions thereof will vaporize without molecular decomposition, substantiallyV separating suchv vapors while removed from heat application from the remaining portions of the oil which do not vaporize without molecular decomposition, passing said vapors in a confined moving stream through an intermediate heating zone possessing a higher temperature than said primary zone to effect the vaporization of the entrained unvaporized oil present in said vapors as a mist or suspensoid whereby said vapors are reduced to a substantially dry moisture free state without appreciable cracking thereof taking place, and then passing said dry vapor in a confined moving stream at a velocity materially greater than the velocity of the vapors in the intermediate zone through an elongated cracking zoneof restricted cross-sectional area whereinv said vapors attain a cracking temperature in excess of 1000 F.

4. The method of cracking hydrocarbon oil into vapor phase, which consists in passing a moving stream of such oil through a primary heating zone and therein heating the oilto a temperature at which portions thereof will vaporize without molecular decomposition, substantially separating such vapors in an externally unheated separating zone from the remaining portions of the oil which do not vaporize without molecular decomposition, passing said vapors in a confined moving stream through an intermediate heating zone possessing a higher temperature than said primary zone to effect the vaporization of entrained unvaporized oil present in said vapors without any appreciable cracking of the vapors taking place, then directly passing said dry vapor from the intermediate heating zone and without reduction in its total weight through an elongated conversion zone "of restricted cross-sectional area, wherein said vapors attain a conversion temperature in eX- cess of T1000o F., and causing the vapors to travel at a materially greater vvelocity through said conversion zone than the vepossessing a higher temperature than saidl primary zone to effect the vaporization of entrained unvaporized oil 'present in said vapors without any appreciable cracking of the vapors taking place, then directly passing said dry vapor` from the intermediate heating zone and without reduction in its total weight through an elongated conversion zone of restricted cross-sectional" area, wherein said vaports attain a conversion temperature in eX- cess of l000 F., causing the vapors to travel at a materially greater velocity through said conversion zone than the velocity of travel thereof through the intermediate drying zona-and utilizing the same products of combustion which are employed to heat the con7'y version zone to a high temperature for heating the intermediate drying zone to a lower temperature.

In testimony whereof we affix our signatures.

AUDLEY E. HARNSBERGER. CLYDE L. SMITH;

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