US2478686A - Apparatus for heating fluids - Google Patents

Description

Aug. 9, 1949.

APPARATUS FOR HEATING FLUIDS Filed Oct. 30, 1944 H. P. DAYTN ETAL 5 sheets-sheet 1 INVENTORAS.

ATTORNEY.

Aug. 9, 1949. H. P.- DAYToN ErAL 2,478,686

y 'APPARATUS FOR HEATING FLUIDS med oct. so, 1944A s sheets-sheet 2 WNVENroRs.

ATTORNEY.

Aug. 9, 1949. P. DAYTON ETAL APPARATUS FOR HEATING FLUIDS 5 Sheets-Sheet 5 Filed Oct. 30, 1944 wv IN VEN TORS.

AU- 9, 1949. H. P. DAYToN ET Al. 2,478,686

APPARATUS FOR HEATING FLUIDS Fired oct. 30. 1944 5 sheets-sheet 4 FIG. 5A. as 24 Q Q.: Q Q. Q. Q

Aug. 9, 1949. H. P. DAYTON ET AL 2,478,686

v 'APPARATUS Fon HEATING mums Filed oct. so, 1944 5 sheets-sheet 5 A BY FlG. s. 'lr.. A ENT.

Patented Aug. 9, 1949 APPARATUS FOR HEATING FLUIDS Herbert P. Dayton, Baytown, and Conrad ILKolienberg, Goose Creek, Tex., assignors to Standard Oil Development Company, a corporation of Delaware Application October 30, 1944, Serial No. 560,964 9 claims'. (c1. 12a- 250) The present invention is directed to an apparatus suitable for heating fluids, and more particularly to a heater adapted for heating hydrocarbon oils containing finely divided solid in suspension therein.

The device of the present invention is particularly suitable for cracking petroleum oils while using the suspensoid technique, wherein a finely divided catalyst is suspended in the oil and the suspension then forced through a heating coil. It is often desirable to conduct the cracking operation wth the oil in a vapor phase, and if the conduit through which the oil is forced to flow contains abrupt turns, there is a decided tendency for the solid material to be thrown to the outside of the turn by centrifugal force, with resultant rapid erosion of the apparatus at the turns. By employing the apparatus of the present invention, higher concentration oi' iinely divided solid catalyst may be employed (with resulting improved cracking) than in the usual return-bend type of coil,since the erosive action is distributed with desirable results over the entire coil rather than in the sharp return-bends.

The device of the present invention may be briefiy described as involving a coll through which the material to be heated is caused to flow. The coil comprises a number of sections having the ends joined together in such a way that they may be readily connected or disconnected. while the furnace is provided with means arranged to shield the points of connection of the sections from the direct action of the combustion gases in tbe furnace used for heating the coil. The coil is arranged in the furnace so that the portion of the coil subject to the more severe eroding action of the suspensoid is heated to a higher temperature than the remainder of the coil, In those portions of the coil subjected to the highest temperatures. coke or carbonaceous solid material is more likely to form and the eroding effect of the finely divided solid is utilized to rernove the coke or carbonaceous material from the coil.

Other obiects and advantages of the present invention may be seen from the following description taken with the drawing, in which:

Fig. 1 -is an elevation partly in section of an embodiment of the present invention;

Fig. 2 is a View yalong line II-II of Fig. 1;

Fig. 3 is an elevation of another embodiment of the present invention;

Fig. 4 is a section taken along IV-IV oi' Fig. 3:

Fig. 5 is a top view, with parts cut away, of

another embodiment of the present invention.

. another embodiment of the present invention.

2 The embodiment of FIg..5 is generally similar in elevation to the embodiment of Figs. 1 and 2.

Figure 5A is an elevation partly in section of the embodiment of Figure 5.

Fig. 6 is a top view, with yparts cut away, of

The embodiment of Fig. 6 is generally similar to that of the embodiment of Figs. 1 and 2.

` Figure 6A is an elevation partlyin section of the embodiment of Figure 6.

Figure 7 is an elevation partly in section of a still further embodiment of the present invention; and

Figure 8 is a view taken along line V-V of Figure 7. I

In the description of the several figures of the drawing, corresponding numerals will be -em'- ployed to designate corresponding parts.

Turning now specifically to the drawing. and first to Fig. 1, a foundation I I is arranged to supportr a furnace wall I2 having a generally cylindrical shape and formed of a suitable refractory material. Concentrically arranged within wall I2 is a second wall I3, having a generally cylindrical shape and spaced a substantial distance within wall I2 to define an annulus I4, which serves as a passage for the combustion gases of the furnace. A helical coil I5, made up of a plurality of sections I6, with each section bent through an angle of 180 and the ends of the sections secured together by flanges I1 to form fluidtight joints, is arranged around the inner furnace wall I3 and is supported thereby. The furnace is provided with a floor I 9 constructed of' a suitable refractory material. The floor is pierced by a plurality of ports 20, with a burner 2I arranged in each port and a conduit 22 arranged to supply each burner with a suitable combustion mixture. The burners are directed upwardly to allow the direction of flow of the combustion gases to be substantially parallel with the longitudinal vaxis of the coil I 5 as well as with the walls I2 and I3. The annulus I4 discharges into an upper zone 23, defined by shell 24. Shell 24 is arranged to direct the hot gases through a preheating zone 25, containing tubes 26, and subseouently discharges the gases into stack 21.

While the inner furnace wall I3 has been described as having a generally cylindrical shape,

the wall departs slightly from such a shape in order to prevent flanges I1 from coming direct- 1y into contact with the hot combustion gases filling space Il. Member I3 is conveniently constructed in two arcuate sections 28 and 29, with each arcuate section extending through substan- 'present invention.

tially less than 180, and the ends of arcuate section 28 joined to straight wall sections 30 extending outwardly from the ends of section 28 and beyond helical coil I5. Similarly, the ends of arcuate section 29 are secured to straight sections 3I extending outwardly beyond helical coil I5. The ends of the sections 30 and 3| are joined by sections 32 extending at right angles to sections 30 and 3|. l Eachwall section comprising units 30, 3| and 32 may be said to form an outset section to shield flanges I1 from the combustion gases. It will be understood that walls 30 and 3| are pierced by a plurality of ports or openings to allow the passage of the turns of helical coil I through said walls.

'I'he two outset sections comprising walls 30, 3| and 32 and spaced approximately 180 apart serve as the supporting means for coil I5. In the drawing the walls are shown as constructed of refractory material and pierced by poits through which the coil extends with each turn of the coil resting directly on the refractory of which these outset portions of the wall are formed. It will be understood that, if desired, metallic hangers may be used to suspend the coil from wall I3 and the ports in the outset portions may be made substantially larger than the outside diameter of the coil, with the space between the openings in the outset portion of the wall and the coil filled by a suitable plugging or calking matcrial to prevent direct contact of the hot gases from space I4 with the flanges Il.

In suspensoid cracking operations it is conventional to vaporize a hydrocarbon feed stock and admix finely divided solid therewith to form a suspension, and pass the suspension through a heating coil. In the drawing either liquid or vaporized hydrocarbon containing the finely divided solid catalyst may be passed via inlet 33 into the lower end of coil I5, caused to flow in a continuous manner through the coil and removed from the upper end thereof via outlet line 34. It will be understood that the apparatus employed for preheating the oil and for forming a mixture of suspensoid in the vaporized oil is conventional to the art, suitable apparatus being disclosed, for example in U. S. Patents No. 2,319,710 and No. 2,322,070, issued to R. K. Stratford and R. H. Smith on May 18, 1943, and June 15, 1943, and accordingly such apparatus is not shown in the description of the furnace of the Similarly, the subsequent treatment of the mixture of thermally treated oil and suspensoid is conventional to the art and is not shown in the drawing.

When it is desired to disconnect the several sections comprising the heating coil, flanges I1 may be disconnected and the coils moved outwardly into space I4 until the ends thereof are free from walls and 3|. It is preferable to employ as coupling means I1 flanges which may be removed from the ends of the coil so that the ends of the coil may pass through openings of substantially no greater size than those through which the sections of the coil pass when the coil is intact. If such removable anges are employed, it will be necessary to disturb the refractory material very little, if at all, in order to dismantle the coil I5. However, if desired, the flange members may be fastened directly to section i5 and portions of the refractory material removed from walls 30 and 3| to allow the passage of the flange members therethrough in dismantling the helical coil, and upon reassembling the coil such openings may be filled with refractory material.

It will be evident that the outside portion of coil I5 receives a substantially greater amount of heat than the inside portion because of the exposure of the outside portion to the radiant energy received from the combustion mixture. In cracking operations, coke and carbonaceus material result at the high temperatures to which the hydrocarbon material being cracked is exposed. and such materials are deposited to a greater extent in those portions of the apparatus subjected to the higher temperatures. When employing the furnace of the present invention for cracking oils there will be a tendency for substantially greater portions of coke and carbonaceous solids to deposit on the outer rather than on the inner side of the interior surface of the coil. The solid material conventionally employed in cracking operations has a density many times greater than the vaporized hydrocarbon preferably employed as the suspending medium, and the ilow of the suspensoid through the coil causes a centrifugal force to be exerted on the solid material which forces it to the outside of the helical coil. Accordingly, that portion of the coil in which there is a greater tendency to form coke is subjected to a greater erosive effect from the suspensoid than is the remainder of the coil, and the scouring effect produced by the solid material as it passes through the coil is. at least in a substantial measure, proportioned to the tendency of coke to deposit on the surface of the heating coil.

It is to be understood that the present invention is not limited to the use of any specific dimensions in the construction of the device nor to the thermal treatment of any specific charging stock nor to any specific charging rate. It will be found, for example, that the diameter of the coil may be varied from less than 20 to greater than feet, as desired. It will also be found that the furnace may be employed for thermally treating a substantial range of hydrocaribons at any desired charging rate. It is preferred, however. to employ a hydrocarbon in the gas oil boiling range as a charging stock and to pass the suspension of vapors and catalyst through the coil at a rate in the order of to 200 feet per second.

Although 'for purposes of description the apparatus has been described as circular in cross section. it is to be understood that the exterior wall of the apparatus may be square or even rectangular in shape. Preferably, however, the outer wall should be substantially parallel to the curvature of the heating coil, since the greater part of the heat imparted to the fluid flowing in the coil is obtained by radiation from the llame and from the outside refractory wall.

The embodiment of Figs. 3 and 4 may be similar to that of Figs. 1 and 2 in the arrangement of the foundation and floor. The coil I5 is made up of sections, with each section defining an arc of approximately and the ends of the sections secured together by flange members I1 in exactly the same way as the embodiment of Figs. 1 and 2.

The outer wail in the embodiment of Fig. 3 is comprised of arcuate sections 35 and 35, with each section deiining an arc somewhat less than 180. The inner wall is comprised of sections 2B and 29 extending through an angle of somewhat less than 180 and corresponding to the sections designated 'by the identical numbers in the embodiment of Figs. 1 and 2. Adjacent ends of sections 28 and 35 are connected by the straight wall sections 31-31, and the adjacent ends of sections 38 denne a second combustion zone.

dened by combustion zone |4 of the embodiment shown in Figs'. land 2. In the embodiment of Fig. 3, burners 2|' are arranged' in each combustion zone I4' with the combustion gases directed substantially parallel to the longitudinal axis of coil I5. The upper ends of the combustion zones I4'-|4' discharge into a shell 24'.,.

which defines a preheating section 25 containing coils 26 and discharges into stack 21. Y

The embodiment of Figs. 3 and 4 conveniently allows the circulation of air adjacent the flange members |1 so that these members may be at a temperature substantially below the temperature of the refractory walls within combustion zones |4-|4'. In this embodiment the flange members may be inspected while the furnace is in operation and maintenance and repair operations may be carried out on this part of the apparatus before the entire furnace has been cooled. It will be understood that the flanges I1 of the embodiment of Figs. 3 and 4 may either be removable to allow the convenient removal of the Vends of coil section I6 through walls 31 and 38,

or alternatively flange member |1 maybe secured to the ends of section I6 in a more permanent manner and the openings in walls 31 and 38 through which coil sections I'6 pass may be enlarged to allow the passage of the flange mem- I 'bers when vremoving or replacing section I6 of the coil.

Another embodiment of the present invention is shown in Fig. 5. Fig. 5 is a top view, with parts cut away, to give a view generally similar to the top View shown in Fig. 2 of the embodiment illustrated in Figs. 1 and 2.

In Fig. 5 a heating coil 40 is made up of 60. sections with six sections making up a complete turn of the coil. The ends of the sections are connected together by flanges 4|. The combustion zone is dened by an inner wall comprising 6 arcuate segments 42 with the ends of the arcuate segments connected together by straight wall sections 43 and 44. An outer tubular wall 45 is spaced a substantial distance away from the inner wall and cooperates therewith to define a combustion zone 46, in which burners 2| are arranged to direct combustion gases substantially parallel with the longitudinal axis of coil 40, as well as parallel to the longitudinal axis of outer wall 45, and the inner wall is comprised of sections 42, 43 and 44. It will be understood that straight wall sections 43 serve to support the segments of heating coil 40.

The embodiment of Fig. 5 is particularly adapted for large furnaces wherein the heating coil may have a diameter as great as 60 feet. The division of each turn of the heating coil into at least 6 segments, with the ends of each segment supported, allows the segments to be made in dimensions which allow them to be readily handled and in addition provide adequate support for the segments in the furnace. In Figure 5A it will be seen that an elevation of the embodiment of Figure 5 is given and the general arrangement of flow of the oil through line 33 and, coil 40 is similar to that described with respect to Figure 1. In this particular embodiment the ends of the six sections making up a complete turn of the coil are enclosed by wall sections 43 and 44 which isolate nanges 4| from the combustion section 48.

It will be seen that the arcuate segments 42 and the straight wall sections 43 Aand 44 are connected to define an inner wall. The inner wall and the outer tubular wall 45 define a combustion zone 46;

' It is usually desirable to construct the heating coil .of the furnace of the present invention with a circular cross section anda vertical axis.

It is also usuallyr desirable to construct the inner furnace wall and the outer furnace wall as tubular members with a generally circular shape.

If desired, however, the axis of the heating coil may be arranged at an angle to the vertical and the plan view of the coil may be in the form of a closed curve -which is not a circle. If the plan view of the heating coil is formed into a noncircular shape, it is desirable that it be generally oval in cross section and that the largest` dimension across the oval be no greater than 1,1/2 times the smallest dimension across the oval. Fig. 6 is a top view, with parts cut away. of another embodiment of the present invention. The elevational View of this embodiment would be generally similar to the elevational view of Fig. 1. It may be pointed out that the principal difference between the embodiment of Fig. 6 and that of Figs. l and 2 is that in Fig. 6 the heating coil is, yin plan view, in the form' of an oval. and nach turn is divided into 4 sections, whereas in the embodiment of Figs. land 2 the heating coil is of lfl. circular section and each complete turn is divided into 2 parts.

In Fig. 6 a heating coil 5| is shown as comprising 4 sections for every complete turn with flanges 52 arranged to connect the'severa'l sections togetherY to form a complete coil. It will be understood that in this embodiment ofthe invention as in precedingly described embodimenta'the heating coil will preferably comprise a substantial number of complete turns. An inner wall is defined by arcuate sections 53 connected Itogether by straight'wall sections 54 and 55 arranged with the arcuate sections 53 within the heating coil and straight wall sections 54 and 55.

forming outset portions to shield the connecting flanges of the heating coil form direct-contact with combustion gases. An ovial shape outer wall 56 is provided which follows the same general shape as coil 5| and the inner walll of the furnace and co-operateswith the inner Wall to deflnea combustion zone. Burners 2| are arranged in the combustion zone 51 to direct the vcombustion gases substantially parallel to the vertical axis of the heating coil 5| and the inner furnace wall. In Figure 6A it will be seen that the outer oval shaped wall follows the general configuration of wall 5| and the inner wall of the furnace to define a. combustion zone 51. The inner wall is divided into arcuate sections 53 which are connected by straight wall sections 54 and 55 with the arcuate sections 53 within the heating coil, straight wall sections 54 and 55 forming outset portions to shield anges 52 'fromdirect contact with the combustion gases in zone 51.

When the heating coil of the furnace is formed in an oval shape as in Fig. 6, it is desirable for the completed coil to delinea pattern contain- The embodiment of Figures# and 8 may 'be generally similar to that of Figures 3 and 4 with the exception that the embodiment of Figures 'l and 8 show a structure generally oval in shape. In Figures 7 and 8 the coil 60 is made up of sections with each section defining an arc somewhat less than 180. The outer wall of the embodiment of Figure '7 comprises arcuate sections 6| and 02 with each section defining an arc somewhat less than 180. The inner wall is comprised of sections 63 and 64 extending at an angle.of somewhat less than 180. Adjacent ends of sections 6I and 63 are connected by straight wall sections --65 and adjacent ends of sections 62 and 64 are connected by straight wall sections 66-$6. Sections 6|, 63, and 65 define a combustion zone 61' and, similarly, sections 62, 64, and 66 define a second combustion zone 61. The two combustion zones are generally arcuate in section and are designated as 61-B1'. In the embodiment of Figure '1, burners 2| are arranged in each combustion zone 61' with the combustion gases directed substantially parallel to the longitudinal axis of wall 60. The upper ends of the combustion zones S'V--Gl discharge into a shell 24 which defines a preheating section 25 containing coil 26 and from' thence discharges into stack 21.

The embodiment of Figures 7 and 8, similar to the embodiment of Figures 3 and 4, conveniently allows the circulation of air adjacent the flange members 68 so that these members may be at a temperature substantially below the temperature of the refractory walls within combustion zones i1'61'. It will be understood that, like the embodiment of Figures 3 and 4, the flanges l! of Figures 'I and 8 may either be removable to allow the convenient removal of the ends of coil 60 through walls B5 and 6B, or alternatively, flange members $8 may be secured to the ends of sections 80 in a more permanent manner and the openings in walls 65 and 88 through which coil sections 60 are passed may be enlarged to allow the passage of the flange members when removing or replacing sections of the coil.

Although for purposes of description the apparatus has been described as circular in cross section, it is to be understood that the exterior wall of the apparatus may be square or even rectangular in shape. Preferably. however, the outer wall should be substantially parallel to the curvature of the heating coil, since the greater part of the heat imparted to the fluid flowing in the coil is obtained by radiation from the ame and from the outside refactory wall.

It will be understood that the number of sections required to be joined together to make a complete turn of the heating coil may be varied over a substantial range. Usually it will be found convenient to use a number ranging from 2 to 6 sections to make a complete turn. That is to say, if the cross section of the heating coil is circular, the sections may conveniently be formed to describe arcs ranging from 60 to 180 and may, of course, include arcs of 90 or 120. Similarly, if the cross section of the heating coil is in the shape of a closed curve, which is non-circular. it will be found convenient to employ from 2 to 6 sections to make up a complete turn of the coil. In general, the larger the cross section of the furnace, the greater will be the number of sections employed to make a complete turn of the heating coil with the sections equally proportioned.

In the elevation of the embodiments of Figs. 1 and 3, the heating coil has been shown as helical. While this is a preferred shape of the coil, it will 8 be understood that the coil is by no means restricted to a helical shape, but that if desired the space between the turns of the coil may be either greater or less than the spaces between the turns of a helical coil.

Having fully described the present invention. what we desire to claim is: l

1. An apparatus for heating fluids comprising, in combination, a plurality of sections of tubing each defining an arc of not more than releasable flange means connecting together the tube sections to form a coil -comprising a plurality of turns, a first furnace wall comprising an arcuate section with the radius of the arcuate section smaller than the radius of the coil and arranged concentric with the coil, a second furnace wall comprising an arcuate section having a substantially greater radius than the radius of the coil and concentric therewith, wall sections co-operating with the first and second furnace wall to define a combustion zone excluding the flanges but including a major portion of at least some of said tube sections, and means supplying air and fuel to the combustion zone and directing the resulting flames and hot gases in a line parallel with the axis of the coil.

2. An apparatus for heating fluids comprising, in combination, a plurality of sections of tubing each defining an arc of not more than 180, removable ange members securing ends of the tubular sections together to denne a coil comprising a plurality of turns, an outer furnace wall member comprising arcuate sections having a radius substantially greater than the radius of the coil and concentric therewith, an inner wall member comprising arcuate sections with a radius smaller than the radius of the coil and concentric therewith, non-arcuate sections in communication with the arcuate sections of the inner member, the arcuate and non-arcuate' members of the inner structure co-operating with the outer structure to define a combustion zone including the major portion of the coil but excluding the flange members and maintaining said flange members in fluid communication with the space-defined within the inner arcuate members, and means for introducing a combustible mixture within the combustion zone and for directing resulting flames and gases in a direction parallel with the axis of the coil.

3. An apparatus for heating fluids comprising, in combination, a plurality of tubular members each defining an arc of approximately 180, removable fiange members securing together ends of the tubular members to form a coil comprising a plurality of turns and having a vertical axis, an outer furnace wall member comprising a cylindrical refractory wall having a radius substantially greater than the radius of the coil and concentric with the coil, an inner wall member comprising two arcuate portions each including less than 180 and with a radius less than the radius of the coil and concentric therewith, wall portions arranged to join together the adjacent ends of the inner arcuate members and to include in the space defined within the inner arcuate members the flange members Joining together the tubular members and means arranged for introducing a combustible mixture into the space included between the inner and outer furnace wall members and to direct resulting flames and hot gases in the space parallel to the longitudinal axis of the coil.

4. An apparatus for heating fiuids comprising, in combination, a plurality of tube sections each denlng an arc of,180. removable flange mem bers securing together ends of the tube members to define a-coil with avertical longitudinal axis, a rst and second arcuate furnace wall member of the same radius and subtending equal arcs including less than 180, said first and second arcuate members being concentric with the coil and having a radius substantially greaterthan the radius of the coil, a third and fourth arcuate furnace member subtending the same size arc as the first and second furnace members but having a radius less than the coil and arranged concentric therewith with the ends of the third membei; and the ends of the first member lying on a line and the ends of the fourth member and the ends of the second member lying on a line, wall members connecting together the adjacent ends of the first andthird and second and fourth members to denne two combustion zones and a third zone separating the combustion zones, the third zone including the flange members connecting together the tube members, and means for introducing a combustible mixture into each of the combustion zones and for directing the resulting names and hot gases in the combustion zone parallel to the longitudinal axis of the coil.

5. An apparatus in accordance with claim 1 in which said coil is circular in plan view.

6. An apparatus in accordance with claim 1 in which said heating coil is oval in plan View.

7. An apparatus for heating fluids comprising,

in combination, a plurality of sections of tubing each defining an arc not greater than 180, releasable flange members connecting together the tube sections to form a heating coil, said heating coil having a vertical axis and including a plus rality o f complete turns with each complete turn in plan view being in the form of a closed curve symmetrical with respect to the axis of the coil, a combustion zone deiined by wall sections parallel with the axis of the coil, said combustion zone including at least a portion of each complete turn and excluding all flange members, at least one of said wall sections being arcuate, within the coil and -concentric therewith, at least an- 1,698,789

other of the wall sections being arcuate, spaced said combustion zone and for directing the resultng flames and hot combustion gases parallel to the axis of the coil.

8. An apparatus in accordance with claim 7 in which the arcuate wall member within the coil is adjacent thereto and in which the combustible mixture is supplied to portions of the combustion zone adjacent the wall member spaced away from the coil.

9. An apparatus for heating iiuids comprising, in combination. a plurality of sections of tubing each defining an arc not greater than releasable flange members connecting together the tube sections to form a heating coil, said heating coil having a* vertical axis and including a plurality of complete turns with each complete turn in plan View being in the form of a closed curve symmetrical with respect to the axis of the coil, a combustion zone dened by wall members parallel with the axis of the coil and additional wall members also parallel with the axis of the coil and spaced from said wall members, said combuston zone enclosing at least a portion of each complete turn, said additional wall members excluding all ange members of said tube sections from said combustion zone, at least one of the wall members being arcuate, outside the coil, spaced away from the coil and concentric therewith and means for supplying combustible liquid to said combustion zone and for directing the resulting flames and hot combustion gases parallel to the axis of the coil.

HERBERT P. DAYTON. CONRAD H. KOLLENBERG.

40 file of this patent:

UNITED STATES PATENTS Number Name Date 558,918 Jones Apr. 21, 1896 Gillican Jan. 15, 1929 2,214,711 Watts Sept. 10, 1940

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