US2258235A - Heating of fluids - Google Patents

Description

Oct 7, 1941- M. w. BARNES 2,258,235

HEATING OF FLUIDS Filed Feb. 19, 1940 2 sheets-sheet 2 Patented Oct. 7,` 1941 u HEATING F FLUIDS Marion W. Barnes, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, corporation -of Delaware Ill., a

Applieauon February 19, 1940, serial No. 319,637

r12 Claims.

The invention relates to an improved form of heater employing high rates of heat transfer `.from flames and hot combustion gases resulting from the combustion of fuel to the uid or fluids undergoing heat treatment and wherein the latter may be quickly heated to high temperatures.

This improved form of heater is particularly advantageous as applied to the heating o normally liquid or normally gaseous hydroc rbons `to the high temperatures required for their conversion and will be found especially useful inv processes for the catalytic conversion of hydrocarbons, such as catalytic- `cracking, dehydrogenation and the like, wherein the hydrocarbon reactants are preheated to a temperature Within the range of pyrolytic cracking prior to their contact with the catalyst and wherein it isqdesirable to preclude any substantialdegree of thermal conversion of the hydrocarbons by substantially limiting the time required to heat them to the desired conversion temperature-and by minimizing pressure drop through the heating coil which also serves to reduce thermal conversion.

The features of the invention and its advantages Will be apparent to those familiar with the art from the accompanying diagrammatic drawings and the following description thereof.

Fig. 1 represents a cross-sectional elevation of one specific form of heater embodying the features of the invention.

Figs. 2 and 3 illustrate modifications of certain portions of the heater shown in Fig, 1,

through firing ports I4 in the roofI of the furnace with each of the zones 6 and 1, is provided above the roof of the furnace adjacent the upper end of each of the Walls I0 and II. The burners and burner ports are so disposed that names and hot combustion gases issuing therefrom are directed against and flow downwardly in the form of a substantially continuous sheet over the surface of walls I0 and II in the combustion zones 6 and 1, respectively, heating the refractory surfaces of these walls to a highly radiant condition.

A fluid conduit comprising plurality of tubular elements I5 is disposed in combustion and heating zone 6 adjacent the inner surface of Wall I and another uid conduit, comprising a plurality of tubular elements I6, is disposed in combustion and heating zone 'I adjacent the inner surface of Wall 2. In the particular case here illustrated,'each of the fluid conduits I5 and I6 comprises a single horizontal row of vertically disposed tubes located in a common plane substantially parallel to the adjacent side wall of the heater. The tubes are connected at their opposite ends to headers I'l and I8 and the tubes I6 are connected at their opposite ends to headers I9 and 20, the headers at one end serving to distribute incoming fluid to be heated to the tubes and the headers at the opposite end serving as a means of removing the resulting heated fiuid from each of the tubes. Thus, for example, the stream of fluid supplied to heaier I8 is divided into a plurality of separate s reams of substantially equal volume which fl W upwardly in parallel through the tubes I5 to eader I1 .wherefrom the heated fluid is discharged, while the same or a separate stream of fluid to be heated in tubes I6 may be supplied to header 20, pass walls, end walls, roof and floor is divided into similar combustion and heating zones 6 and 1 and a central zone 8 leading to stack 9 by refractory walls I0 and II spaced apart to form'zone `8 andspaced centrally between walls I and`2 to form zones 6 and 1. Walls I Il and II each exv tend from the iioor 4 to the roof 5 and extend between Ythe end walls. They are each provided with openings I2 therethrough adjacent the oor Y bustion gases passing through zone 6 and from' the hot refractory surface of Wall I0 and are heated on the opposite side by re-radiation from the refractory inner surface of wall I I. Tubes I6 and the fluid passing therethrough are heated on one side of each ofthe tubes by direct radiation from the flames andhot combustion gases. in zone 'l and from the hot refractoryvsurface 0f wall II and on the opposite sideby renected radiation from the refractory inner surface of 'Wall 2. The tubes I5 and I6 are also heated substantially by direct contact with hot combustion gases passing through lthe respective zones 6 and 1 but with' the arrangement of burners,

with adjacent tubes in each row connected either l. in parallel' or in series. Qn the other hand, all

burner ports and combustion gas ports herein provided, the tubes I5 and I6 are out of the direct path of travel oftheflames and hottest combus tion gases passing through vthe combustion and heating zones andlocalized overheatingI of the tubes with its'attendant disadvantages and dangers is thereby prevented.

The combustion gasesl which have .passed through zones 6 and 1 and therein Vgiven up a substantial portion of their heat to tubes I5 and I6, respectively, and the uid passing therethrough are directed through ports I2 in the respective walls I0 and II to zone 8 wherein'the gases from both combustion and heating zones commingle andare directed therefrom to stack 9 Preferably, in order to improve the `-thermal efciency of the heater and increase the flameburst` temperature, to increase radiant heat transmission, heat is transferred from the iiue gases to lthe air utilized to support combustion in zones 6 and 1. I his is accomplished, in the case here illustrated, by providing an air y,preheater 2I between the upper discharge end of zone 8 and stack 9. This air preheater may be of any desired conventional form and air for Vof the tubes of the bank wmay be connected in parallel by means of suitable headers at their opposite ends or the tubes of each individual row may be connected in series and the two rows connected in parallel.

A single row'of horizontally disposed tubes connected either in parallel or in series may be employed, when desired, in either or both of the zones 6 and 1, in place of the vertical tubes shown in Fig. lor the two rows of horizontal tubes shown in Fig. 2. The invention also contemplates employing two rows of vertical tubes in zone B or in zone 1 or in both and with eithera single or double row of vertical tubes the tubes may be connected either in series or in parallel.

combustion is drawn from the atmosphere through the'preheater in indirect heat transfer` zone 8 to stack 9, the preheated air being sup` xTheinvention also contemplates disposing another uid conduit within zone 8 of the heater shown in Figl. 'I'his is illustrated in Fig. 3 wherein the reference' numerals corresponding to .those in Fig. 1 designate corresponding portions of the furnace structure.

In Fig. 3, the fluid conduit 53 disposed inzone 8 comprises a plurality of superimposed horizontal rows of horizontally disposed tubes 54 with adjacent tubes, in adjacent rows arranged in staggered formation. The tubes of bank 53 are disposed in the 'direct path of iiow pf combustion gases passing from .combustion zones 6 and 1 through zone 8 and serve'to materially reduce the temperatureof the stack gases, thereby implied .to chambers 22 within which burners I3- afe disposed and the inductor action of the burnersy serves to draw airfrom; chamber 22 through the burners into zones 6 and v`'I and around the burner tips through the firing ports I4 into zones 6 and 1.

Itis alsowithin the scope of the invention to provide a duct 23 adjacent wall I and a duct 24 adjacent wall 2 through which air admitted thereto through the respective openings 25 and 26 passes along the side walls of the heater to cool the latter and thus be preheated. Ducts\2,3 and 24 communicate through ducts 21 and 28,

respectively, with the air inlet ports 29 and 3Ileither or both of the combustion zones 6 and 1.`

One alternative form of iluid conduit, which,

however, is not to be considered the equivalent of that shown in Fig. l, is illustrated lin Fig.2,

' Fig. 2 may be considered asectionalelevation of a portion of the same furnace `structure shown in Fig. 1, including a combustion zone Iigfandcorresponding partsi in the two figures arel designated bythe same reference numerals; The tube bank 5I here illustrated comprises two substantially parallel vertical rows of horizontally dis--l posed tubes 52 with adjacent 'tubes in the opposite rows arranged in staggered formation.' Bank 5I is rdisposed adjacent and substantially parallelto side Wall I of the heater.

Any d'esired conventional-1 arrangement, not

illustrated, ,of connecting tubes of. bank 5I may be'employed within the scope of the invention.

may be connected Vat vtheir. ends in series by means of any suitable form of return bends or e the case here illustrated, for admitting air, when l proving Ithe thermal e'iciency of the heater, it being within the scope of the invention to employ vbank 53 with orwithout `a subsequent air pre- 6 or'zone 1 may be supplied, while a separate stream of uid subsequently supplied to the uid conduitlof the other combustion z one is passed through the remaining portion of bank 53 or j the entire bank 53 or any desired portion thereof 50' maybe utilized for separately heating a differ-Y entstream lof fluid than that supplied toV either of the fluid conduits in zones I5 and 1.

Since no novelty is claimed herein for the speciiic sequence of flow through the various conduits for the specic use to ,which they are put nor the manner of connecting the individual tubular elements in' each bank, the many various alternative but non-equivalent arrangements Iabove mentioned vin conjunction with the description of Figs. 21 and 3 are omitted to avoid unnecessary complication of the drawings.

Referring to Fig. 4,` the heater here illustrated instead of having separately red combustioni .zones'has a single combustion and heating zone 33 defined by' side walls 34 and35, licor 36, roof 31 and end walls whichV do not appear in this For example, adjacent tubes in opposite rows particular View of theh ater.

Burners'38, arranged'in a row .adjacent the upper end of wall 35, supply a. combustible mixvture of., fuel and air to zone 33 through iiring the two separate rows may be connected in series; heating thexlatter to a 'highly radiant condition,

'amazes Combustion gases are directed from the lower portion of zone 33 through openings 40 provided in the lower portion of wall 35 to flue 4l communicating with stack 42. :An air preheater 43 is disposed Within the flue. Air is admitted to the air preheater through duct 44 and passes therethrough in indirect heat transfer relation with the combustion gases passing to the stack and the preheated air is supplied from air preheater 43 through ducts 45 and 46 to chamber 41 in which burners 38 are disposed, the preheated air being supplied to and around the burners to combustion zone 33. Duct 46, in the particular case here illustrated, is disposed parallel Vto and in contact with the exterior surface of Wall 35 and heat transmitted through this wall is supplied to the stream of air passing through duct 46.

A fluid conduit which, in the particular case here illustrated, comprises a single row of vertically disposed tubular elements 48 communicating at their opposite ends with headers 43 and 50 is disposed adjacent wall 34 outside the main path of ow of the flames and hot combustion gases passing through zone 33. The tubular elements 48 are eachheated on one side by direct radiation from the ames, hot combustion gases and hot refractory surface of Wall 35 and are heated on the opposite side by reflected radiation from wall 34. They are also subjected to heating by convection from the combustion gases in zone 33.

It is also within the scope of the invention to employ a fluid conduit like tube bank 5i of Fig. 2 in combustion zone 33 of Fig. 4 or, when desired, a single vertical row of horizontally disposed tubes may be substituted in Fig. 2 or in Fig, 4. I also contemplate using, when desired, two vertical rows of vertically disposed tubular elements in combustion zone 33 of Fig. 4 or in either or each of the combustion zones 6 and 1 of Fig. 1.

The invention also contemplates the use of a separate fluid conduit disposed in combustion gas passageway 4I of a furnace of the general /form illustrated in Fig. 4, in which case air preheater 43 may be retained or omitted. Also, when desired, a relatively narrow vertically disposed combustion gas passageway, similar to zone 8 o f Fig. 1, may be substituted for zone 4| of Fig. 4 with or without a fluid conduit similar to tube bank 53 of Fig. 3 in this zone.

The alternative specific forms of heaters above mentioned are not specifically claimed hereinvand are, therefore, not illustrated.

It will be understood, of course, that with any of the specific furnace structures illustrated and/or above described, means similar to that illustrated may be .provided for preheating air utilized to support combustion within the combustion zone or zones or, when desired, particular- 1y in case a separate fluid conduit is utilized in the combustion gas passageway from the combustion `zone or zones to the stack, the air preheater may be omitted.

I claim as my invention:

l. A heater for fluids comprising an elongated substantially. vertical combustion zone defined by side walls, end walls, a roof and a floor, a plurality of tubular fluid conduits disposed adjacent one of said side walls and spaced from the opposite side wall to provide said combustion zone therebetween, burner means adjacent one end of said opposite wall and arranged to forcibly direct flames and hot combustion gases vertically over and in'intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adjacent the vend thereof most remote from said burner means, a passageway for combustion gases communicating at one end through said openings with the combustion zone and communicating at its opposite end with a stack.

2. A heater for fluids comprising, in combination, an elongated substantially vertical combustion zone defined by side walls, end walls, a roof and a floor, a plurality of tubular fluid conduits disposed adjacent vone of said side walls and spaced from the opposite side wall to provide said combustion zone therebetween, burner means adjacent one end of said opposite walland arranged to forcibly direct flames and hot combustion gases vertically over and in intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adjacent the end thereof most remote from said burner means, a passageway for combustion gases communicating at one end through said openings with the combustion zone and communicating at its vopposite end with a stack, an air preheater Adisposed in the path of flow of the combustion gases passing from said passageway to the stack and means for passing air subsequently supplied to said combustion zone through said air preheater.

3. A heater for fluids comprising, in combination, an elongated substantially vertical com-7 bustion zone defined by side walls; end walls, a roof and a floor, a plurality of tubular fluid conduits disposed adjacent one of said side walls and spaced from the opposite side wall to provide said combustion zone therebetween, burner means adjacent one end of said opposite wall and arranged to forcibly direct flames and hot combustion gases vertically over and in intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adn jacent the end thereof most remote from said burner means, a passageway for combustion gases communicating at one end through said openings with the combustion zone and communicating at its opposite end with a stack and another fluid conduit comprising a plurality of tubular e1e' ments disposed in said combustion gas passageway.

4. A heater for fluids comprising, in combination, separate elongated substantially vertical combustion zones each defined by refractory side walls, end walls, a roof and a floor, corresponding side Walls lof the separate combustion zones being spaced apart in substantially parallel relation to form a combustion gas passageway therebetween, said corresponding side walls having openings therethrough adjacent one end thereof, through which openings communication is established between said separate combustion zones and said combustion gas passageway, burner means adjacent the opposite end of each of said corresponding walls and arranged to forcibly direct flames and hot combustion gases over said corresponding side Walls in a substantially vertical direction from the end of said corresponding side Walls most remote from said openings therethrough and fluid conduits disposed adjacent the other side Wall of each of said combustion zones.

5. A furnace for the heating lof fluids comprising, in combination, separate elongated substantially vertical combustion zones each defined by refractory side walls, end walls, a roof and a floor, corresponding side walls of the separate combustion Zones being spaced apart in substantially parallel relation to form a combustion gas passageway therebetween, said corresponding side walls having openings therethrough adjajacent one end thereof, through which openings communicationis established between said separate combustion zones and said combustion gas passageway, burner means adjacent the opposite end of each of said corresponding walls and arranged to forcibly direct names and hot combustion gases over said corresponding side walls in a substantially vertical direction from the end of said corresponding side walls most remote fromsaid openings therethrough, iiuid conduits disposed adjacent the other side wall of each of said combustion zones and another uid conduit disposed in said combustion gas passageway.

6. A heater for uids comprising, in combination, separate elongated substantially vertical combustion zones each defined by refractory side walls, end walls, a roof and a floor, corresponding vside walls of the separate combustion zones being spaced apart in substantially parallel relation to form a combustion gas passageway therebetween, said corresponding side walls having openings therethrough adjacent one end thereof,

Athrough which openings communication is established between said separate combustion zones and said combustion gas passageway, burner means adjacent the opposite end of each of said corresponding walls and arranged to forcibly direct iiames and hot `combustion gases over said corresponding side walls in a substantially vertical direction from the end of said corresponding side walls most remote from said openings therethrough, uid conduits disposed ,adjacent the other side wall of each of said combustion zones, a stacky communicating with said corn--y bustion gas passageway, anair preheaikr in the path of flow of combustion gases passing from said passageway to the stack and means for passing air subsequently supplied to said combustion zones through said air preheater.

7. A heater for uids comprising, in combination, substantially vertical side and end walls, a

roof and a iioor, substantially vertical refractory interior walls extending between said end Vwalls and from the roof to the floor, said interior walls being spaced from each other and from said side walls to provide a combustion zone between each interior wall and the nearest side wall and provide a. passageway for combustion gases between said interior walls, iiuid conduits disposed adjacent each of said side walls out of the main path walls opposite the burners, an air preheater disposed in the path of ow of combustion gases passing from said combustion gas passageway to a stack, means for passing air through said preheater in indirect heat exchange relation with said combustion gases and means for supplying resulting preheated air to the combustion zones.

8. A heater for fluids comprising, in combination, separate combustion zones each having a rality of substantially vertical tubular uid conduits disposed adjacent one of saidside walls means adjacent one end of said opposite wall and aangaat substantially vertical. red wall and a substantially vertical uniired wall spaced apart and disposed in substantially parallel'relation with each other, fluid conduits disposed within said combustion zones adjacent each of said unred Walls, burner means adjacent one end of each of said fired walls and arranged to forcibly direct flames and hot combustion gases in a substantially vertical direction over the surface of said fired walls, a combustion gas passageway communicating with each of the combustion zones at the end thereof remote vfrom said burner means, an air preheater disposed in the path of flow of combustion gases passing from said combustion gas passageway to a stack, means for admittingair toV said air preheater and passing the same therethrough in indirect heat exchange relation with said combustion gases and means for delivering resulting preheated air to said combustion zones.

9. Aheater for fluids comprising an elongated substantially vertical combustion zone defined by side walls, end walls,- a roof and a floor, a pluand spaced from the opposite side wall to provide said combustion zone therebetween, burner arranged to forcibly direct fiames and hot com- -bustion gases vertically over and in intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adjacent the end thereof m'ost remote from said burner means, a passageway for combustion gases communicating at one end through said openings with' the combustion zone and communi- Y arranged to forcibly direct :dames and hot combustion gases vertically -over and in intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adjacent the end thereof most remote from said burner means, a passageway for combustion gases communicating at one end through said openings With the combustion zone and communicat- 'ing at its opposite end with a stack.

. through and disposed adjacent one of said side walls and spaced from the 'opposite side wall to provide said combustion zone therebetween, burner means adjacent one end of said opposite wall and arranged to forcibly direct flames and hot combustion gases vertically over and in intimate jacent the end thereof most remote from said burner' means, a passageway for combustion 'gases communicating at oneend through said openings with the combustion zone and communicating at its'opposite end with a stack.v

12. A heater for uids comprising an elongated substantially vertical combustion zone deiined by side walls, end walls, a roof and a door, a plurality of substantially vertical tubular fluid conduits connected for the parallel ow of separate streams of uid therethrough disposed adjacent one of said side Walls and spaced from the opposite side wall to provide said combustion zone' therebetween, burner means adjacent one end of A said opposite wall and arranged to forcibly direct 10 names and hot combustion gases vertically over and in intimate contact with the surface of said opposite side wall facing said conduits, said opposite side wall being provided with openings therethrough adjacent the end thereof most remote from said burner means, a passageway forvcombustion gases communicating at one enu through said openings with the combustion zone and communicating at its opposite end with a stack.,

` MARION W. BARNES.

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