US1547993A - Pressure still - Google Patents

Description

July 28, 1925.

J. r.-:. BELL ET AL PRESSURE STILL Filed Jan. 17, 1921 s Sheets-Sheet 1 I jzvezzar July 28, 1925. Y Y 1,547,993

J. E. BELL ET AL PRESSURE STILL Filed Jan. 17. 1921 "351186125-511681. 2

July 28, 1925. 1,547,993 I J. E. BELL ET AL PRESSURE STILL 4 Fi1edJan. 17, 1921 3 Sheets-Swat 5 in/Enjoy Patented July 28, 1925..

UNITED s TEs JOHN E. BELL, OF BROOKLYN, NEW

YORK, AND EDWARD w. Isom, or WINN'ETKA,

ILLINOIS.

rimssvnn 'srILL.

Application filed January 17, 1921. Serial No. 487,662.

To all whom it may concern:

Be it known that we, JOHN E. BELL and vEnwi'uto WV. ISOM, citizens of the United States, residing, respectively, at Brooklyn,- county of Kings, and-State of New York,

and WVinnetka, county of Cook, and State of Illinois, have invented certain new and useful Improvementsin Pressure Stills, of

which the following is a specification.

The pressure stills to which our invention relate are designed to crack petroleum, gas oil and other heavy hydrocarbons and to convert them as far as possible into lighter hydrocarbons such as those constituting the fraction known on the market asgasoline. In the operation of cracking such heavy hydrocarbons they are heated up to very high temperatures, commonly under high pressure, with the result that the heavier oils, or a portion thereof, are broken downforming lighter oils which are vaporized and -driven ofi. The vapors are condensed and submitted tofurther treatment to form the commercial product. In the formation of the lighter oils carbon is freed ordeposited in considerable quantity remaining behind in the heavy oil and tar in the still and on the heat absorbing surfaces of the latter with which the oil is in-contact. The carbon and protection afforded by the .oil so that theheavy tar are very oor' conductors of heat 'and when deposite upon the heating surfaces of the ,still which are exposed to the heating gases insulate the surfaces from the heating surfaces are apt to become over,- heated, the temperature of the metal surface increasing over the temperature of the oil to an extent dependent upon the thickness of the carbon deposit and the amount of heat externally delivered tothe heating surface from the furnace. As a consequence unless stills are frequently shut down for cleaning or the temperature of the furnace reduced below that which is most ellicient, it is difiicult to maintain the stills in operation for a suflicient length of time to'make such operation commercially practidal. There 1s also considerable hazard to life and propertybecause of the possible bursting of the over-heated portions of the still, which is increased because of the pressure usually maintained in such stills which may be as much as one hundred pounds per square inch or more.

The surfaces of the still most exposed to the heat of the furnace are of course most apt to suffer, and in the. case of a tubular still,

towhich our invention more particularly relates, the tubes which receive the greatest amount of heat from the furnace by reason of their location, suffer the most. It is one of the objects of our invention to provide an improved apparatus for cracking oil in which the heating tubes exposed to the products of combustion from the firebox at the highest temperatures contain oil which is substantially free from carbon and'tar, the

oil as it accumulatestar and carbon and loses its content of crackable hydrocarbons flowing successively through heating tubes exposed to products of combustion from the furnace at successively lower temperatures, thus enabling the still to be operated for a greater length of time between cleanings than is possible with the construction heretofore known.

With this object in view we provide a tank body or drum containing the main body of oil to be cracked and connected as usual to a condenser in which the vapors constituting the desired fraction are condensed. The

drum is provided with transverse partitions of any desired number which separate the oil contained in the still into different bodies,

v and the oil to be cracked is fed-to the first compartment and overflows from the first conta ned. The respective compartments are provided with heating tubes so connected thereto that the oil in each compartment circulates through the heating tubes which appertain thereto and back to the compart- 'inent, the sets of heating tubes being arranged successively in the flues of the furnace so that those appertaining to the compartment first receiving the flow of oil are subjected to the highest temperature and succeedingv sets of tubes are subjected to progressively decreasing temperatures.

In order that the vapors of the desired composition may be developed approximately in equal quantities in the several compartments and the temperature of the oil 'itself maintained, the number or total length of heating tubes is increased successively from the first to the last compartment. This arrangement also provides a large extent of surface on which carbon can be deposited in the coo-lest part of the still where it is least likely to be baked toa hard crust.

The circulation of the oil from the drum or the compartments thereof through the heating tubes and back to the drum may be caused or assisted by pumps or other mechanical means, or convective action due to the effect of heating and generation of vapors and fixed gases may be depended on for this purpose, either method of circulation being within our invention in its broader aspect, and the invention is correspondingly broadly defined in certain of the following claims; in a companion application Serial No. 459,555, filed April 8, 1921, we have set forth and specifically claim such a construction in which forced circulation is provided, but in the present instance we have set forth and in the more specific claims covered a construction in which natural circulation or convective action are relied upon In the accompanying drawings we have shown and in the following s ecification described in detail a preferre form of the apparatus of the invention. It is to be understood, however, that the specific disclosure is for the purpose of exemplification only and that the scope of the invention is defined in the following claims in which we have endeavored to distinguish it from the prior art so far as known to us without, however, relinquishing or abandoning any portion or feature thereof.

In the drawings each part is identified by the same reference character wherever it appears in the several views.

Fig. 1 is a vertical longitudinal section of a preferred form of still embodying our invention on the broken line 11 of Fig. 2 parts being shown in elevation; .Fig. 2' a transverse vertical section of the same upon the line 22 of Fig. 1; and Fig. 3 a horizontal section upon the broken line 33 of Fig. 1.

The still drum 4 in the referred form of the invention illustrated is supported upon I-beams 5 upon the furnace structure 6. The latter comprises a fire-box 7 which may be of any known or approved construction and a series of vertical flues 8, 9, 10, 11, the first of which is connected at its lower end to the fire-box and at its upper end to the second flue, the latter being connected to the third fine at its bottom and the third flue 10 being connected at its top to the last flue 11 which at its lower end is connected to the stack fine 12. Drum 4 is divided into a series of compartments corresponding to flues 8 to 11 by partitions 13 and a battery of heating tubes is connected to each compartment and depends into the corresponding heating flue directly beneath the same so that the oil in each compartment is separately heated. In addition to the openings between the heating flues described above additional openings 14; and 15 controlled by dampers 16 and 17 may be provided in the walls between said flues as found desirable to further regulate and control the heat distribution among the several heating lines.

In order to avoid exposing the first group or battery of heating tubes in the flue 8 to an excessive temperature from the freshly formed products of combustion rising from the fire-box we provide means for dilutin the highly heated gases with any desire amount of waste gases taken from the lower end of the last flue 11 near the exit to the stack, which gases have been considerably cooled by the passage through the heating flues in contact with the oil heating tubes, but still retain some available heat. For this purpose we have shown a passage or conduit 18 connecting the bottom of flue 11 with a space 19 immediately behind bridge wall' 20, the passage or conduit being provided with a venturi or other known forcing device. By returning a proportion of the spent gases not only is the heat of the freshly formed products of combustion tempered but economy in fuel is accomplished by reason of the further utilization of the available heat remaining in the returned gases and the increased volume or mass of gases brought into contact with the heating tubes in a given time.

Each of the compartments of the drum is provided with three complete heating units each of which comprises an out-flow header 21 and an inflow header 22 both 0011- nected into the bottom of theparticular compartment of the drum with which they are associated and sets of inclined heating tubes 23 and 24, the tubes of the former set being connected to the outlet header 2i and inclining upwardly therefrom and the tubes of set 24 being connected to the inlet header 22 and extending downwardly therefrom, corresponding tubes of the re- I spective sets being connected to ether at the opposite side of the furnace from said headers by unions25 (see Fig. 3). In order to facilitate cleaning and repair the headers and unions are arranged beyond the heating chamber as shown in Fig. 2 and formed with plugged hand holes 26 and 27 in alignment with the respective tubes for access to the latter. In operationthe relatively cool oil in the compartments flows downwardly through the outlet headers 21 into the pipes 23 and thence by unions into the pipes 24 and inlet headers 22, the heating of the oil in the upwardly inclined pipes 23 and 24, and the development of gases and vapors therein causing a circulation of the oil upward through said pipes and headers 22 and consequently downward through header 21. In order to provide for drainage andthe withdrawal of tarry. matter formed during the distillation and cracking of the oil the lower ends of headers 21 .are

connected into a'manifold 28 and may be drained thro'ughthe outlet elbow 29. The

"lower ends of the headers in the last compartment are connected-to the manifold 33 and outlet 34to the tar draw off line, and if the still is operated continuously tar of predetermined density may be continuously drawn off through this line.

As the products of combustion decline'in temperature during their progress through the heating flues from the firebox to the stack the absorption of heat by the oil .in successive compartments would correspondingly decline werenoprovisio-ns made to the contrary. As it is desirable that the cracking effect he as nearly uniform as practicable'throughout the. several compartments we offset or compensate for the decline in temperature of the products of combustion as they progress along theiheating flues by increasing the number of heating tubes in the units in the successive vertical headers.

In the specific apparatus shown the heating units identified. with the first compartment of the drum and located in the first heating flue 8 have four tubes to the set, those in the second heating flue have eight tubesto' the set, those in the third heating flue have twelve tubes to the set, and so on. -The surface for deposition of carbon and tar also thus increases with the content thereof in the oil. I

The drum is shown as provided with the usual reflux tower 32 from which the vapors escape through vapor-line 33 and which may receive oil to be treated through inlet pipe 3 1 The tower is located over the first compartment so that condensate flowing therefrom is returned tothe latter., The drum is provided with an inlet pipe 35 leading into the first compartment and whether oil be supplied through inlet 34' or inlet 35 it flows immediately .into the initial c'ompartment. pletely shut off the compartments from each other but extend a short distance above the level at which the oil is to be maintained,

the vapor space being open throughout the drum. The second, third and fourth compartments receive their respective charges through over-flow pipes 36, 37 and 38 opening through the respective partitions. Bells 39 over the over-flow pipes extend a proper distance below the top of the latter to retain the scum and froth on the surfaceof the oilin the respective compartments and pre The partitions 13 do not com-' vent it transferring into the succeeding compartments. g

The fresh oil is received in the first com partment and is-partially cracked therein, the vapors given ofl as, well as'the vapors from the other compartments passing into the reflux tower which condenses and returnsthe fractions which are insufficiently cracked to the first compartment. As fresh oil is fed in a certain amount of the oil from the first compartment which has been deprived of a portion, at least, of its more readily cracked component and contains some tar and carbon continuously overflows into the second compartment where afurther portion of its components is cracked and vapor1zed,'a port1on of what remalns being continuously fed to the third compartment, and so on, the oil in successive compartments containing less and less material which responds to the cracking operation and more and more heavier material. 'The oil-heating tubes connected to'the first compartment and arranged in the firstheating flue are subjected to the highest temperature of the products of combustion as heretofore pointed out, but this does not result in an excessive deposit of carbon or separation of fixed gases and tarry matter because the oil in the first compartment and circulating through such tubes contains the maximum amount of components which will easilyv crack without forming free carbon. The oil in the second compartment contains a smaller percentage of crackable components than that in the first compartment but the deposition I of carbon and release of fixed gas is not excessive because the lighter molecules are still being cracked without forming carbon to any great extent. The oil in the third compartment containing less crackable hydrocarbon and more tarry matter and the like is subjected to a lower heating te'mperature than the oil in the second compartment, and so on. At the same time by reason of the greater exposure' of heating surface in successive compartments and flues the cracking effected in the respective compartments is more or less equalized, and the surface for depositing carbon is increased in the temperature.

&

, to the other compartments, means for leading off the vapors developed in the respective compartments, a furnace having an elongated heating flue, a corresponding series of separate heating coils arranged along the length of the heating flue and connected to the respective compartments of the drum for heating the oil therein whereby the oil is subjected to successively decreasing temperatures.

2. In a still, a drum, partitions therein dividing the drum into a series of communicating compartments, means for feeding oil to be cracked to the first of said series of compartments and permitting it to flow successively into the other compartments, a furnace having a heating flue,'a corresponding series of separate heating coils arranged in said flue at successively increasing distances from the fire box and connecting respectively to the successive compartments of the drum to heat the oil therein, the coil connected to the first compartment be ing arranged to receive the first contact of the products of combustion of the furnace.

3. In an oil still, a drum to receive the oil to be cracked, partitions in the drum,

dividing it into a series of communicating compartments, means for feeding oil into the first of said series of compartments,

and permitting it to flow successively into' the other compartments, a furnace having an elongated heating flue, a corresponding series of separate heating coils connected respectively to the successive compartments of the drum and located in the heating flue, the coils being arranged in the heating flue successively to receive the heating gases in the same order in which the compartments with which they are connected are arranged in the drum.

4. In an oil still, a drum to receive the oil to be cracked, partitions dividing the drum into a series of compartments communicating both below and above the normal liquid level, means for feeding oil into the first of said series of compartments, a reflux condenser communicating with the vapor space above the several compartments and arranged to drain into the first of said series of compartments, means for feeding oil into the said first of the series of compartment's, a furnace having an elongated heating flue, a corresponding series of separate heating coils connected to the respective compartments of the drum and located at progressively increasing distances from the fire-box in the heating flue, the coils of the said first compartment being armemes ranged adjacent to the fire-box to be first impinged upon by the gases from the firebox.

5. In an oil still, a drum to receive the oil to be cracked, partitions in the drum dividing it into a series of communicating compartments, means for feeding oil into the first of said series. of compartments, and permitting it to flow successively into the other compartments, a furnace having an elongated heating flue, a corresponding series of separate heating coils connected to the respective compartments of the drum and located in the heating flue, the coils being arranged in the latter to be impinged upon by the heating gases from the furnace in the same order as the compartments with which they are connected receive the oil, the successive heating coils being of increasing heat absorptive surface to offset the decline in temperature of the heating gases along the heating flue.

6. In an oil still, a drum to receive the oil to be cracked, a series of transverse partitions dividing ,the drum into compartments, separate heating means for the oil in each compartment, means for introducing oil at one end of the drum and withdrawing residue from the other, an overflow pipe from each compartment to the next in the series, the inlet end of each overflow pipe being materially higher than the outlet end thereof.

7.. In an oil still, a drum to receive the oil to be cracked, partitions in the drum dividing it into a plurality of communicating compartments, a furnace having a heating flue extending substantially longitudinally of the drum, a series of independent pipe coils connected with the respective compartments and arranged at successively greater distances from the firebox of the furnace within a heating flue thereof, the heating surfaces of the respective coils increasing with their respective distances from the firebox.

8. In an oil still, an elongated drum, means for feeding oil into one end thereof and drawing off residue from the other end thereof, means for condensing a portion of the vapors formed and returning the condensate to the feed end of the drum, a furnace beneath the drum having its fire box adjacent the feed end and its outlet adjacent the draw-ofi' end of the drum, means for transferring heat from the products of combustion in the furnace to the contents of the drum at successive points longitudinally of the latter.

9. In an oil still, an elongated drum, means for feeding oil into one end thereof and drawing off residue from the other end thereof, means for partially separating the oil in the drum into a plurality of bodies. provisions permitting the flow of oil from one body to the next past the lastv said ,means, the upper portion of the drum providing an uninterrupted passage for vapors from end to end thereof, means for leading off the vapors formed, a furnace beneath the drum-having heating passages extending substantially the length of the latter,

, a fire box communicating with the passages adjacent the feed end of the drum and an outlet from the passages adjacent the drawoff end of the drum, and heating coils connected to the drum at intervals along the length thereof and extending into the heating passages of the furnace.

. 10-;-In an oil still, an elongated drum,

means for feeding oil into one end thereof and drawing 011' residue from the other end thereof, a reflux tower arranged to communicate with the feed end of the drum, a series of partitions dividing the lower. por; tion of the drum into a longitudinal series of compartments, the upper portion of the,

of the drum and an outlet from said passages adjacent the draw-ofl' end of the drum, and circulating heating coils connected to the respective compartments and extending into the heating passages of the furnace.

- 11. In an oil still, an elongated drum,

' means for feeding oil into one end thereof and drawing-off residue from the other end 'ipartmentsand adapted to discharge into the thereof, partitions dividing the lower part of the drum into compartments but leaving the upper portion of the drum uninterrupted for the passage of vapors along the same,

' means for drawing off the vapors formed, a

furnace beneath the drum having a series of connected heating flues arranged beneath and corresponding to the respective compartments of the drum, a fire box connected to said flues adjacent the feed end of the drum, an exhaust fiue connected to said .heating flues at the draw-ofl' end of the drum,sand a series of heating coils extending from the respective compartments into the flues beneath the same, the heat absorbing surfaces of the coils' increasing successively from the feed to the draw-off end of-the drum.

12.111 an oil still, an elongated drum, means for feeding oil into one end thereof and drawing 013? residue from the other end thereof, partitions dividing the lower part of the drum into compartments but leaving the upper portion of the drum uninterrupted for the-passage of'vapors along the same, means for drawing offthe vapors formed, a

connected heating flues arranged beneath furnace beneath the drum havinga series and corresponding to the respective compartments' of the drum, a fire box connected to said flues adjacent the feeding end of the drum, an exhaust flue connected to said heating flues at the draw-ofl end of the drum, and a series of heating coils extending from the respective-compartments into the flues beneath the same, each*c0i1 comprising a pair ofv headersvat one side of the heating flues and series ofjinclined pipes extending across the, flues and connected to said headers.

13. In an oil still, a furnace having a heating flue, a drum adapted to contain a charge of oil, a reflux tower communicating the heating flue and connections for circulating oilfrom and to the drum therethrough, a separate heating means communicating with the drum arranged in the heatwith the drum, heating means arranged in ing flue between the first mentioned heating a means and the furnace, connections for introducing fresh oil into the reflux tower, and means for initially circulating the fresh oil and admixed reflux'through the last mentioned separate heating means.

14. In an oil still, a drum, partitions therein dividing the drum into compartments, there being openings in the partitions through which the compartments communicate, a furnace having aheating flue, heating units in the flue connected to the respective compartments, means for supplying oil to be treated to one of said compartments and causing it to flow successively to the other compartments .and areflux tower adapted to receive the vapors from the various comcompartment provided with means for sup-,

at one end of said drum, means for with drawing residue from the compartment at K the other'end of said drum, a reflux tower arranged to discharge into the compartment at the first said end of thedrum and adapted to receive the vapors from all of said compartments, a furnace havin a heating flue and-heating units connecte to the several compartments res ectively and extending into said heating ue, the heating unit connected to the-compartment at the first said end of the drum being arranged in the heating flue nearest the furnace.

16. In an oil still,'a drum, titioh's in the drum dividing the same mto transverse parsuccessive communicating compartments, means for feeding 011 mto the first of said compartments atone end of the drum, a

' furnace having a fire box and'a series of flue corresponding to the first said compartment, heating units located in the respective flues and connected to the respective compartments, supplemental passages connecting said fines and valves arranged in said passages for controlling the passage of products of combustion therethrough.

JOHN E. BELL.

EDWARD W. ISOM.

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