US2348181A - Petroleum heater - Google Patents

Description

May 2, 1944. F. H. PRAEGER PETROLEUM HEATER Filed 4June 8, 1942 3 Sheets-Sheet 2 m n N m l n M `al 1w j?. A mf fw May 2, 1944. F. 1| PRAEGrl-:R 2,348,131

PETROLEUM HEATER Fi1ed June 8, 1942 5 Sheets-Sheet 5 F/G. 5 y

J6' I l f INVENTOR.

BY Few/wr b. Rems-6m w71) a) Patented May 2, 1944 PETROLEUM HEATER Frank H. Praeger, Merian, Pa., assignor to Alcorn Combustion Company, Philadelphia, Pa., a corporation of Delaware Application .lune 8, 1942, Serial No. 446,300

10 Claims. l l(Cl. 122-240) My invention relates to heaters, more particularly to heaters of the type used by heating petroleum, its components, andY similar fluids, and has for an object the provision of a heater, the heating capacity of which is large in comparison with the cubical content of the heater.

In my concurrently led application Serial #446,298, and entitled Petroleum heater, I have disclosed and claimed heaters having a plurality of tubes disposed in rows along thev roof and iloor of each re chamber together with an intermediate row of tubes extending horizontally across each lire chamber. In my concurrently filed application Serial #446,299, entitled Method and means of supporting heater tubes, I have disclosed and claimed fluid-cooled pillars which provide for the support of the intermediate bank of tubes. l

In accordance with my 'present invention, a plurality of lstreams of still-burning gases are di-y rected horizontally between adjacent tube banks. These gases travel across the tube banks and exit through outlets located substantially in line with the intermediate row or bank of tubes, after which the gases traverse a convection section for the absorption of additional heat therefrom. The intermediate bank of tubes is supported by means of tube sheets supported at each end by steel columns and intermediate its ends by means of pillars having distinctive and novel features of design which will be more fully set forth hereinafter. I

For a more complete understanding of my invention, reference is to be had to the drawings in which:

Fig. l is a sectional elevation of a heater embodying my invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a section taken on the line 3-3 of Fig. l;

Fig. 4 i's an enlarged elevation, partly in section, of one of the intermediate supporting pillars, and illustrates certain of the parts in positions prior to iinal assembly;

Fig. 5 is an enlarged elevation, partly in section, illustrating the nal positions of the parts which mechanically interconnect the intermediate tube sheets; and y Fig. 6 is a view taken on the line 6-6 of Fig. 4.

Referring to Fig. 1 of the drawings, I have shown my invention in one form as applied to a pair of heaters Ivand Il disposed back to back on either side of a common convection section I2.

The heater I0 is provided with a bank of roof 55` tubes I3 supported from structural steel and by tube sheets' in the usual manner. Similarly, a bank of oor tubes I4 is supported adjacent the floor I5. An intermediate row or bank I6 of horizontally extending tubes is supported by means of a tube sheet I'I secured at one end by suitable means such as the angles I8 to an external steel column I9 which forms a part of the external steel framework (not shown).

The intermediate tube bank I6 functionally divides the heater I0 to form one fire chamber between the banks I3 and I6 and another re chamber between the banks I4 and I6. By means of a plurality of muilles 20, streams of still-burning 'combustion gases are directed horizontally across the upper re chamber and intermediate the tubes of banks I3 and I6. Suitable fuel, such as gasor oil, is introduced into each mule 20 by means ofburners 2I, each provided with a control valve 2Ia; Similarly,l muftles 22 direct horizontally across the lower fire chamber streams of still-burning gases which result from the introduction of fuel into the muflies by means of burners 23, each controlled by a valve 23a. As shown in Figs. l and 2, four muies 20 and four muflles 22 extend horizontally along the front wall 24 of.

the heater I0, although as many may be provided as needed for a particular length of the tubes.

To increase the capacity of the heater IU, the tubes of each bank may be made longer, with concurrent increase inthe number of mullles and burners. Enough burners and munies are provided to insure the burning of the desired amount of fuel in streams of gases which extend generally horizontally across andbetween the tube banks. By sub-dividing theifuelv streams and by directing the still-burning gases by means of muflies 20 and 22, convection contact with the Vtubes of the banks sto large extent avoided. By increasing the number of muiiles, the desired amount of fuel may be burned within' the fire chambers to provide for the release or -generation of the required amount of'heat which, by way of example, may vary from twenty to one hundred million B. t. u.s per hour. The fuel is partially burned within the mules themselves to insure complete combustion thereof and in avoidance of undesirable secondary combustion of fuel in and around oil-conducting tubes.

The streams of gases extend generally across the respective re chambers and exit therefrom through ducts or openings 30, which extend horizontally along the rearv wall 3l of the heater I0 and to large extent they coincide or are in alignment with the intermediate bank I6. In consequence, the streams of gases flow across each fire chamber and toward the openings and in avoidance of all tubes. In fact the flow is largely away from both the roof and rloor banks I3 and I4 and although towards the intermediate bank I6, the tendency of the gases to flow upwardly or downwardly across the tubes of bank I6 is avoided. Since the gases are Withdrawn through the open ings 39, rising gases from the lower muiiles 22 meet descending gases from the muflies 2!) and any tendency of a material or substantial ilow of gases over the intermediate tubes is counteracted.

As shown in my said application Serial tir4=46,298,V

separate exit openings may be provided intermediate'the respective re chambers, but in accord with my present invention the particular location of the two openings or ducts 30 results, with the proper control of draft, in thesubistantial avoidance of convection transfer with the intermediate tubes. Overheating of tubes by simultaneous application of radiant heat and variable Vand excessively high rates of heat transfer by convection heat'is avoided. Preferable the stack draft and the setting of each damper 25 is such that there is Vpositive-flow of gases along the paths described above.

. As explained more at vlength yin my co-pending application, Serial#446,299, particular attention must be given'toth'e 1support ofthe intermediate bankl of tubes, In accordance'with my present inventionfthectubesheet I'I'is' supported intermediate its ends on two pillars 32 and 33 .of identical construction andvonly one-of which,- the'pillar"32, needs be' described in detail.' 'The pillar 32 comprises ahoilow metal membersuch as the pipe 34;.thebase of which is rigidly'secured, as by Y.welding,atoaihollow steel member such as the pipe 35,. itself zembedded inrtheconcrete 'floor 36 of the heater"v I): The pipe. 35rconn'e'cts; with a header i371'for .the ingress Vof! cooling air :or steam, which passes'throughthe pipe 35 andintothe supporting pipes of each oflthepillars 32 and 33. The air vexitsfroml theupper end. of the pipe 34 at a point above `the roofi 38lof` the heater I D. Thoughthe natural draft may. be adequate to insure iiowfof. a' suiiicient quantityv of cooling air, it is to. be understood that' a fsmall' fan (not shown) Y may ibe utilized,l for. example, in the header 37,.orla small amount of'steam may be introducedfdirectly into the pipe 35` by means of asteamjet (not shown). Inl any event,a cooling mediumis oirculated'rthrough the pipe 34v in amount adequate. toV maintain its temperature belowthat at which. it 'would '.lose: a largefpart. of its' strength. r The @pipe 34 is surrounded by ceramic Y refractory wheat-.insulating "material '39 which, as shown in Fig,l 4, .maybe semi-circular in shape :or it may be ofi segmental form. The heat insulation together with the. circulation of the oooling'mediummaintains the metal pipe :34 safely within its normal working .range of -temperature.. .For heaters designed for high temperature operation, it` will'of course beunderstood that. pipe34. aswell as the tube sheets may be of heat-resisting a1loy f As- -best shown in Figui-1, 5, and 6, the tub sheet iT isr preferably made in three or more parts. For example, section `I'Ia extends from the steel column I9 of Fig. 1 to the pipe 34, Fig- 4, and. there terminatesin, or has welded to it, a

semi-circular shape 40 whose inner diameteris slightly larger 'thanv that of tube 34.v Similarly, the tube sheet section I'Ib. terminates in a semicircular-shape 42.". In order to4 anchor and support tube sheet sections I'Ia .and I'Ib` in fixed posiv the elements 43a and 43h partially encircle and lock in fixed position the shapes 4I) and 42, while :the slight clearance provided between the parts provides for. some expansion. A second coupling member 45,v of .identical construction with that of .member 43 is,l during the construction of the heater, moved from the position shown in Fig. 4 to its nal position as shown in Fig. 5 and its two circular elements similarly encircle and lock into position the shapes 40 and 42 of the tube sheets I'Iolan'd Hb.. InFig.5 only one of. such elements, the element 45a, isfshown'...` The coupling member: 451need notbefwelcledv to .the pipe 34. It is to be understood'that coupling elements46 and 41 rigidly interlock :and support the respective ends of tube-sheet sections I Ib and IIc, as shown in Fig. 1.

The main. structuralor weight-bearing member of pillars? of coursecomprises the-'pipe 34. The wall .thickness of the pipe is selected with reference to. its height andthe-weight itis to support. Its inner diameter-is determined with reference to the character and quantity of cooling medium to be circulated therethrough', In a typical. embodiment of myrinvention, pipe 34 may have ari-.inner diameter of four inches; a wall thicknessof one-half inch, for a-lre chamber 10 or 12 feet in height. From 25 to 30 cubic feet of air. per minute may be readily circulated therethrough, or :a mixture of low temperature steam and air` may be used. Where the pipe 34 is of ordinary carbonv steel it is desirable to provide for additional cooling in orderito keep the temperature of the pipek within'its safe working range, whereas for a pipe or-structural member of an alloy -including substantial percentages of nickel and chromium, less cooling isv required Vsince the strength of such an alloy does'not decrease with temperature as rapidly asthat of carbon steel. In either case, the refractory heat insulation surrounding the tube or structural member 34 preferably has a thickness of approximately 4 inches.

Insofar as shown in Fig. l, the heater II is of substantially identical construction with the heater In and I have therefore marked corresponding parts with the same reference numerals as for the heater I 0, except that to most of them there has been added thereto the subscripta.

The combustion gases from the respective heater I0 and II pass directly into a convection section common to both heaters First, the gases pass in convective heat exchange with a bank of tubes 5B andv thenin heat exchange with a bank of ytubes 5I. The tubes 5I` are'shown of smaller diameter and in some cases this may be desirable for a petroleum heater, or the'tubes 5I may be used for the heating of steam. The convection section terminates at the base of a stack 52 only ample, where low pressure y tor-an inlet header 54 a fractional part of which is shown inFig. 1.

A heater embodying my invention is particularly well adapted for the solution of certain unusual and dimcult heating problems. For eX- V y Y drop is a prime requisite, all of the tubes-I3 may be directly connected as shown in Fig. 2. The entering fluid, hydrocarbon gases or hydrocarbon vapors, in subdivided streams owsthrough the several roof tubes I3 and by means of a series of return bends `55 thenriiows directly through corresponding intermediate tubes I 6, thence by way of return bends 56 flows through corresponding floor tubes I4" and into a collecting or outlet header 51. The vapor or gases may be rapidly and uniformly heated to high temperature `with a minimized low pressure drop, of theorder of a few pounds per square inch. Heat is yuniformly applied substantially solely by radiation to the roof tubes I3 and to the oor tubes I 4. Heat is uniformly and to large extent applied by radiation to the intermediate tubes IB and substantially uniformly throughout the entire circumference thereof. It is to be further observed that the small amount of heat transferred to the tubes I6 by convection or by movement of hot gases over them is relatively uniform and the tendency toward hot spots or excessive application vof heat is avoided.

It is to be understood that the tubes may be connected for any desired fiow of fluid therethrough; as for example, the tubes I3 may be interconnectedby means of headers for serial iiow through the roof bank and thence for serial ow through the intermediate and oor tube banks I6 and I4. As shown in my co-pendingapplication Serial #446,298, there may be more tubes in the intermediate bank I6 than in either the roof or floor tube banks. For example twice as many tubes I6 may be provided, in which case all of the tubes I6 could be connected to an inlet header, with every other tube I 6 being connected to a floor and a roof tube, with outlet headers interconnecting the floor and roof tube banks. Such an arrangement would provide for a further decrease in pressure drop for given conditions.

An alternative arrangement of flow is shown for the heater II in Fig. 3. Conventional header boxes 60 are illustrated in single line and headers are enclosed therein for the interconnection of the tubes of the respective banks I3a, IBa. and Ida, the bank I3a being connected by means of transfer line 6I to the bank IBa and the latter connected by transfer line 62 to the oor tube bank Ida. The foregoing serially connected tubes may also be connected in series with tubes 5U in the convection section. In Fig. 3 it will be observed the tube sheet IIa is shown as a structural member of I-shape, although other suitable structural shapes may be used for the tube sheets. It will be observed from Fig. 3 that the outlet openings 30a are located on either side of the tube sheet I'Ia and it is to be understood that the tube sheet exten-ds through the inner wall 3Ia of heater II and that it is anchored to a steel Icolumn in manner as shown for the steel column ISa. Similarly'the tube sheet Il extends through the rear wall 3| of heater IIJ and is supported by a similar steel column (not shown).

While I have shown embodiments of my invention, Vit is to be understood I do not limit myself thereto, but by the appendedclaims I intend to cover all modifications which fall Within the spirit and scope of my invention.

What I claim is:

1. In a heater having refractory walls, the combination of banks of tubes disposed in single rows and respectively adjacent to opposite Walls thereof, an intermediate bank of tubes disposedin a single row intermediate said first-named banks,

fuel burners disposed intermediate the adjacent banks'for directingstill-burning gases between and across and generally in spaced relationfwith said banks, and outlet means for the flow of gases from said heater extending along the side of said intermediate bank remotely located from said fuel burners for restricting the flowof the outgoing gases generally to the region of said intermediate bank. Y l

2. In a heater, the combination-of walls forming a fire chamber, a bank of roof tubes and oor tubes disposed horizontally along the roof and floor of said fire chamber and an intermediate bank of tubes extending generally horizontally across said fire chamber, a plurality of burners for directing streams of still-burning gases generally horizontally between said roof and said intermediate banks, and between said floor and said intermediate banks, and means for withdrawing gases from said fire chamber comprising'outlet means restricting the flow of gases from said fire chamber to a region remote from said burners and generally within the horizontal plane of said intermediate bank of tubes.

3. The combination set forth in claim 2, in which said intermediate bank of tubes is supported by means including a tube sheet, said tube sheet extending beyond the iront and rear walls of said fire chamber, vsaid withdrawing means being located on either side of said tube sheet for the substantial avoidance of convection contact of the gases with said tube sheet.

4. The combination as setforth in claim 2, in which the tubes of said intermediate bank are interconnected and supported by a tube sheet subdivided into sections, supporting pillars intermediate each section, and coupling members extending in interlocking relationship with each pillar and said tube sheet sections.

5. In a heater having refractory walls forming a fire chamber, the combination of a bank of horizontal tubes disposed adjacent the roof and the floor of said fire chamber, an intermediate bank of horizontal tubes disposed between said roof and floor tube banks and as a bank extending generally across said re chamber and spaced from said roof and floor tube banks, a plurality of burners spaced horizontally along the front wall of the heater for directing a plurality of streams of burning fuel above and below said intermediate bank of tubes and in spaced relation with, and to a large extentl in avoidance of, the tubes of each of said banks, andmeans including an outlet passage through the rear wall of the heater for `withdrawing combustion gases, said outlet passage extending along said rear wall and generally coinciding with the horizontal extent of said intermediate bank.

6. In a heater having refractory Walls forming a fire chamber, the combination of a bank of horizontal tubes disposed adjacent the roof and the floor of said fire chamber, anv intermediate bank of Vhorizontal tubes disposed `between said roof and floor tube banks and as a bank extending generally across said fire chamber and spaced from said roof and floor tube banks, a plurality of burners spaced horizontally along the front wall of the heater for directing a plurality of streams of burning fuel above and below said intermediate bank of tubes and in spaced relation with, and to a large extent in avoidance of, the tubes of each of said banks, a tube sheet for said intermediate bank of tubes extending across said nre chamber and beyond the front and rear walls thereof, outlet passages for withdrawing flue gases disposedfonoppositesides-of,` andY in lspaced relationwth, Sadtube sheet,eachsaid Vsaid intermediate bank.Y

7. The combination asset forth in claim 6, in which said tube sheet is supported in part by an intermediate pillar, and meansv for circulating Va cooling medium through said pillar. y

8. The combination as set forth inclaim 6, in which said tub-e sheet is supported intermediate its ends upon a pillar, said pillar comprising a tubular membersupported below the floor of said chamber kand .extending vertically through the re chamber and above the roof thereof, refractory heat-insulation surrounding said pillar and shielding it from the heat of said re chamber, and means tfor producing a flow of a cooliner medium through ysaid tubular member to prevent loss-ofrstrength due to excessive rise of the temperature thereof. Y

9. In a heater, the combinationof walls forming re chambers disposed back to back and a separate convection section intermediate said re chambers, a bank of horizontal tubes extending across and intermediate each of said fire cham bers, and banks of roof and iloor tubes respectivelydisposed;adjacent tothe roof and'floor of each said re -chambenfuel burning means disposed in` horizontal rows above and below said intermediate banks of tubes fordirecting a plurality `of `streams ofistll-burning gases above and Ibelow said intermediate banks-,of tubes and in avoidance of `all of -said banks of `tubes ineach of said -refchambers, openings` in" each of the rear wallsof said re chambers generally coincidingwith the location of each said-,intermediate bank of tubes, ductsleading from each of 1said openings to said convection section, and tubes Within said .convectionsection heated. by convectionfromdzhe. combined currents of combustiongasesfrom said fuel ,burning means.

10. Means for supportingan intermediate bank of. tubes within are chamber, comprising a tubular member, extendingv vertically through said nre` chamber, a tube sheet for said intermediate bank of Vtubes terminating. atl its end in a semicircular kshape for partly encircling .said tubular member, means supported by said tubular member and disposed in interlockingengagement with saidsemi-.circular shapes for holding them in placek and, for supporting a part of `the loaden Said tube sheetspand means forproducing flow of a cooling medium through said tubularmember.

" FRANK H. PRAEGER.

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