US2342011A - Furnace for heating fluids - Google Patents

Description

Feb. 15, 1944.

J. H. RICKERMAN Filed A ril 10, 1941 5 Sheets-Sheet l lNVENTOR 1 BY% a ATTORNEY Feb. 15, 1944.

J. H. RICKERMAN 5 Sheets-Sheet 2 Filed April 10. 1941 JOHN 11mm mam/Wm.

lNVENTOR FIG. 2 l

ATTORNEY Feb. 15, 1944.

J. H. RICK'EJRMAN 7 Filed April 10, 1941 5 Sheets-Sheet 5 INVENTOR avg; I

ATTORNEY Feb. 15, 1944. J, H .RICKERMAN FURNACE FOR HEATING FLUIDS 5 Sheets-Sheet 4 Filed April 10, 1941 FIG-4 F 175,1944- J. H. RICKQERMAN 7 2,342,011

FURNACE FCSR HEATING FLUIDS Filed April 10, 1941 5 Sheets-Sheet 5 JOHN HERMHN RIC/(ERMHM INVENTOR ATTORNEY be released within Patented M15, 1944 UNITED STATES PATENT OFFICE FURNACE fi rmo FLUIDS John Her man Rlckerm'an,

River Edge, N. J... as?

signor to The M. W. Kellogg Company, Jersey City, N. J., a corporatio n of Delaware ApplicationtApi-il 10, 1941, Serial No. 387,199

7 Claims. (Cl. 122-356) 1 This invention relates to the heating of fluids and to apparatus therefonand is particularly concerned with the heating 0 hydrocarbonfluids by; passage thereof through v connected tubes located in a combustion chamber. I

In'the designof oil heating furnaces of the latter type it is constantly necessary to reconcile as far as, possible three essential requirements which are in conflict with each other. The cost of a furnace is'to a great extent dependent upon its dimensions, each square foot of wall and roof area requiring the expenditure of a certain amount of money for the refractory or other material of which it is'constructedand for the steel necessary for its support. The first requirement is therefore that a furnace be made as small as possible in order to reduce construction' costm Present methods of liberating ,heat by combustion being what they are, however, there is a limit to the amount of heat which can a given cubicvolume without the development of excessively high temperatures, which would hasten the disintegration of refractory and metal parts located therein and produce undesirable effects upon the fluid to be heated. The second, requirement, therefore, is

plurality of interthat the combustion chamber of a furnace be made sufliciently large to avoid destructively .high temperatures locally thereof. To a certain extent the latter two requirements may be rec;-

struction wherein the three requirements enu-- merated will .be reconciled to a superiorde'gree, in order that hydrocarbon ofls may more efllciently and at lower cost.-

types by its sloping side walls and its approximately triangular vertical cross section. These features give the structures. shape which rebe heated edge upward. It is contemplated by the invention to position parallel interconnected tubularconduits for fluids to be heated horizontallywith- .in thecombustion chamber defined by the wedgeshaped structure, adjacent and substantially parallel to the sloping walls thereof. The invention further contemplates positioning additional fluid heating tubes within the combustion chamber adjac'ent the upper narrow portion thereof, so as to make upa tube bundle occupyingthespace between the converging side walls. Additional features contemplated by this preferred embodiment of the invention include a multiplicity of separate burners located in a horizontal plane parallel to anct approximately coincident with the bottom of the combustion chamber. These burners are arranged inrows paralleling the fluid heating tubes and are provided with means for controlling the amounts of fuel supplied to the b ers in the individual rows; Products of combustion travel upwardly from the floor of th combustion space,

and after .passing between and around the tube bundle in the converging portion emerge from the top of the combustion chamber into a suitable conduit leading to a stack. c

The advantages of the furnace structure herein disclosed are many in number. Support for the refractory walls of the combustion chamber and for the tubes may be provided with exterior structural members having the so-called A-shape used in the bents of bridges and trestles which, as

is well known, is superior from the standpoint of strength and rigidity. Aside from the purely load-supporting advantages of the Iwedge-shape construction, highly advantageous tube arrangements and methods of firing are thereby made possible. In prior known furnaces of more or less rectangular cross-section, no matter where the burners arelocatedthere is great irregularity and asymmetry in thedistances of difierent tubes from the burners. In such furnaces the differing distances of the tubes from the burners cannot be compensated for by individual adjustment of The furnace structure of my invention, in its i sembles that of a truncated or blunt wedge, resting upon its back with its truncated narrower the burners. It is impossible to liberate heat in the corners of a rectangular furnace if all the tubes are tobe heated at a high and uniform rate, and such dead spaces reduce, the mean rate of heat liberation for the furnace as a whole. In my improved furnace, however, there is a regular divergence between rows of tubes and rows of burners.- Since the burner rows are individually controllable, I may regulate the amounts of fuel supplied to and lengths of the flames issuing from the burners in proportion to their distances from the tubes, and thereby liberate a maximum amount of heat'in all parts of the combustion chamber, without great variation in the rate of heating from tube to tube.

Other objects and advantages of the invention will appear during the course of the more de-' tailed description now to be given with reference Fig. 3 is an isometric view of still another type of structure alternate to Figs. 1 and 2; I 1

Fig. 4 may be considered a sectional end elevation of any one of the three furnaces shown in the first three figures showing one optionaltube arrangement and the locationof burnerswith respect thereto; 1

Fig. 5 is an isometric phantom view in detail of one type of burner assembly suitable for use in connection with the invention; 1 I

Fig. 6 is a purely diagrammatic representation of an alternate tube arrangement capable of being embodied in .the structures shown in the preceding drawings, and

Figs. '7 and 8 are further diagrammatic tube arrangements exhibiting various features within the scope of the invention.

ucts at the top of the combustion chamber is unobstructed by any structural members such as I02 and 202 as in Figs. 1 and 2. The weight of the refractory walls 305 and 309 is transmitted by the stays 30I and braces 303 to girders 304 extending along the tops of the inclined walls.

The girders 304 in turn transmit the load to the main top cross member 302 at the extreme ends of the frame. An elongated stack breeching 30! collects products of combustion along the entire upper portion of the combustion chamber and conveys them to duct 308 which may lead to a stack or other apparatus such as an air preheater or economizer.

It will be understood that the furnace structure of my invention is not limited to the particular proportions and arrangements shown in Figs. 1 to 3. In general I mayemploy wedge- In Fig. 1 six I-beams IOI of which only four are by smaller beams I03 intermediate their length.

The tops of beams IOI are additionally braced by members I04 so that the assemblage consistingof members IM to I04 forms a supporting frame for refractory walls I05 and I09 enclosing a combustion chamber. A header box I06 has a counterpart concealed from view on the the opposite end of the structure and covers the connections between the ends of tubes located along the sloping walls and adjacent the roof of the combustion chamber. Stack breechings I01 communicate with the interior of the com- .bustion chamber and are adapted to convey products of combustion therefrom into the stacks I08. It will be observed that the structure shown in Fig. 1 employs relatively short roof supporting members I02 by reason of its converging side walls. Their short length decreases their weight and cost relative to the roof. members used in prior known furnaces having broad flat roofs.

In Fig. 2 the method of framing shown is identical to that of Fig. 1 comprising inclined members 20I, top cross members 202, braces 203 and 204, refractory walls 205 and 209 and header boxes 206, but embodies a single bifurcated stack breeching 201 which surrounds the middle one of the three top cross members 202 while providing an air tunnel therefor to permit air cooling thereof. The construction of Fig. 2 may be employed when it is desired that only the one stack 208 be used.

Fig. 3 embodies a more extensive departure from the structures already described but still partakes of the advantages of the invention. In this structure the exit area for combustion prodshape structures of varying lengths and heights and thereby provide furnaces of any desired capacity. When long furnaces are used the stack arrangement of Fig. 1 will be preferable, while with the shorter lengths the breechings of Figs. 2 and 3 may suitably be employed.

In Fig. 4, which, as previously mentioned, represents a sectional end elevation of any one of the structures shown in Figs. 1 to 3, the inclined beams 40I support refractory walls 0 and rest upon suitable footings 4II. Tubes 2 are arranged in parallel rOWs longitudinally of walls M0 and hence appear in Fig. 4 as circles. Burn,- ers 4l3 are arranged in rows, only the ends of which are visible, and. are individually controllable row by row as will be hereinafter more fully described, so that they may receive fuel at different rates and-produce flames of graduated height as shown. Because of the locus of tubes 4 I2 relative to the burners, they will receive heat predominantly by radiation and hence may be referred. to as radiant tubes, in accordance with the usual furnace nomenclature. Tubes 4 are situated'approximately at the apex of the section and are nested closely together so that hot products of combustion liberated by burners 412 must pass at relatively high velocity between and around them. They will receive heat predominantly by convection and are properly described as convection tubes.

The advantages of my improved furnace structure in enabling a maximum rate of heat liberation throughout a combustion chamber will be readily apparent from a view of Fig. 4. The centrally located rows of burners being farthest from heat absorbing surfaces may feasibly produce flames of greater intensity so as to effect a high rate of heat liberation in those regions of the combustion chamber not occupied by nor lying adjacent to any parts subject to overheating. At the same time the rows of burners at the sides of the combustion chamber may be fired less vigorously so as to protect the steel and refractory parts in close proximity thereto while utilizing the available volume for the liberation of appreciable quantities of heat. This arrangement facilitates systematic heat distribution to all the tubes of the sloping radiant banks. All the combustion products converge on the convection tubes 4 and acquire a high velocity by reason of the constricted upward passageway so that a maximum amount of heat can be recovered therefrom before release into the stack or stacks. In the particular tube arrangement shown in Fig. 4 fluid to be heated may be introduced into the interconnected rows of tubes in two parallel streams by way 'of inlets H9 and the the apex of the cut that t is tube arrangement insures that the two. strea' will be heated identically-as the two streams traverse equal numbers of substantially equally furnace.

Fig. illustrates one type of burner arrange- .ment suitable for use in connection with the furnace of Fig. 4. 5l5 represents a slab or foundation of concrete or refractory of alength equal to that of a combustionchamber. This base is recessed or slotted as shown to provide support bustible material released by. any one of the pipes 5I3 running longitudinally heated tubes before leaving the The burner pipes are provided with withdrawn from outletsll8. It will be apparburner pipes may be individually controlled by" means of the respective valves. Air for the combustion in controlled amount is supplied either by natural, forced, or induced draft through air ducts 5 I 1 extending perpendicularly of the burner pipes" through the foundation slab iii and openinginto the recesses in which the burner pipes lie.

gIt'is to be understood that the burner arrangement shown in Fig. 5 is purely exemplary as numerous other constructions for producing inand be adapted for use in connection with in e tion. l

In Fig. 6 I have shown an alternate tube arrangement for producing identical heating. of two parallel fluid streams wherein a greater number of tubes are .used in the convection bank. The .radiant tubes BIO are disposed as in Fig. 4 but the'convection tubes 6' fill in the apex of the combustion chamber relatively completely. The arrangement in Fig. 6 in comparison with that of Fig. 4 illustrates how the relative'sizes of the radiant and convection sections. may be varied within a given furnace volume.

Allthe usual methods of adjusting the rate of heating of a fluid stream or streams may be available of in connection with my improved structure as, for example, the use of double rows of tubes in a radiant bank. ment is shown by Fig. 7 as it might be used. to

heat a single'fiuid stream. .The radiant tubes 1 ll] are conventionally arranged but the convection section embodies a feature of the. invention which may be-of particular value when a high efficiency is desired in a relatively small convection section. Asindicated by the figure, convection tubes 1| 4 have been arranged in a relatively narrow bundle centrally located within structure. What would normally be free space on either side of the bundle is filled in with refractory so'that products of comv bustion are required to traverse a relatively constricted path through the convection tube bundle. By this means a higher velocity and improved heat transfer is afforded. Moreover by stepping in the refractory filler as shown and making the tube bundle progressively narrower with height. the combustion gases are given anincreasing velocity concurrent with lowering of their temperature by heat transfer. In this manner the tendency for heat transfer to decrease with temperature may be counteracted and heating made more uniform throughout the convection bank.

Fig. 8 illustrates still another modification of the tube arrangement contemplated by the in- Such an arrangelike.

. 30 divid ally controllable rows of flames are known to the base. I radiation between the two sides of the furnace. Convectiontubes 8 are arranged compactly in 'velo city and 8") are arranged in a single row along the entire height of the left handwall of the furnace while on the right hand wall they are arranged in a not extend all the way A bridge wall 820 minimizes crossdouble row which does a manner alternate to that of Fig. 7 between projecting refractory corbels to provide higher creased heat transfer for the products of combustion passing therethrough.

'The improved furnace construction of my invention is capable of receiving a variety of mechanical expressions and may inconporate a greater number of separate fluid heating circuits in any one furnace than have been indicated in the drawings. invention is of particular advantage in connection with hydrocarbon conversions effected at elevated temperatures such as thermal and catalytic cracking,.polymerization, reforming and the It may advantageously be used to heat hydrocarbon oils prior to distillation thereof and may'incorporate in a common combustion chamber both oil heating and steam generating coils. It is to be understood furthermore that I am not limited by any of the examples given herein for purposes of illustration.

I claim:

1. In a furnace for heating fluids, the combination which comprises a combustion chamber having a fiobr, a furnace wall bounding said chamber and inclined inwardly with respect thereto, a

" pluralit'yof fluid-conducting conduits disposed two adjacent said wall, a plurality of burners located in said fioorand adapted to project products of combustion upwardly directly therefrom toward said wall, and means for controlling the firing of erally toward theconvergence of said walls, and

means for controlling the firing of said burners to effect less intensive firing of said burners closest to said sloping walls than those farthest from said sloping walls.

4. A furnace as in claim 3 wherein saidedges are the lower edges of said walls and said burners are directed vertically upward.

5. A furnace for heating fiuids comprising a furnace floor, two side walls rising upwardly and inwardly toward each other at acute angles from opposite sides of said floor, two. end walls rising from the other two opposite sides of said our, said four walls and said floor enclosing a combustion chamber having a relatively broad base and a relatively narrow opening for the escape of combustion products between the uppermost edges of said inclined side walls, corbels projecting inwardly from said side walls just below said opening so as to enclose between them a narrowed passage forcombustion products ap- While not limited thereto, my

proaching said opening, a plurality of interconnected conduits for fluids disposed adjacent and parallel to said side walls, a plurality of like conduits relatively compactly disposed within said passage, a plurality of burners adapted to produce hot products of combustion for saidcombustion chamber and means for controlling the firing of said burners to effect less intensive firing of said burners closet to said rising walls than those r refractory-walls bounding two sides of said chamher and having a relatively narrow opening between their uppermost edges for the escape of combustion gases, a plurality of fluid-conducting conduits disposed adjacent said refractory walls.

and means for controlling the firing of said burners to eifect less intensive firing thereof closest to said sloping walls than those farthest from said sloping walls.

7. A furnace for heating fluids which comprises a combustion chamber iimited in one direction by a burner setting, a plurality of inwardlydirected burners in said setting, the cross-sectional area of said chamber in a plane coincident with said setting being greater than in any I parallel planeappreciably distant from the plane of said setting, sloping refractory walls bounding two sides of said chamber in other directions and w provided with an opening opposite said burner setting for the escape of combustion products, a

plurality of fluid-conducting conduits disposed v adjacent said walls, and means for controlling the firing of said burners to effect less intensive firing thereof closest to said sloping walls than 20- those farthest from said sloping walls.

J. HERMAN RICKERMAN.

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