US2108687A - Heating of fluids - Google Patents

Heating of fluids Download PDF

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US2108687A
US2108687A US694960A US69496033A US2108687A US 2108687 A US2108687 A US 2108687A US 694960 A US694960 A US 694960A US 69496033 A US69496033 A US 69496033A US 2108687 A US2108687 A US 2108687A
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furnace
combustion
fluid conduit
firing
zone
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Lev A Mekler
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Universal Oil Products Co
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Universal Oil Products Co
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    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G9/00Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G9/14Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
    • C10G9/18Apparatus
    • C10G9/20Tube furnaces

Definitions

  • This invention relates to an improved apparatus for the heating of fluids and more particularly refers to an improved form of furnace and heating method especially adapted for the heating' of hydrocarbon oils to the high temperatures required for their pyrolytic conversion.
  • this flexibility is attained in, a simple .furnace structure by a special arrangement of the fluid conduit and special flow of oil therethrough in combination with a method for controlling combustion,conditions in the furnace, particularly with respect to the length, luminosity and other characteristics of the flame produced.
  • One specific embodiment of the apparatus may, comprise a main furnace structure having end walls, side walls, a roof and a floor, a combustion zone within said furnace, means forsupplying a, combustible fuel-air mixture to the combustion zone, means for separately supplying controlled quantities of additional air to said combustion zone, a convection heating zone located within the furnace and separated from the combustion zone by a bridge wall, means for removing-combustion gases from said furnace through the convection heating zone, a fluid conduit comprising a plurality of horizontal rows of serially connected, horizontally disposed tubular elements located within said convectionheating zone, a fluid conduit comprising a horizontal row of serially connected, horizontally disposed tubular elefurnace,
  • a fluid conduit comprising a, horizontal row of seriallyconnected, horizontally disposed tubular elements located adjacent the floor of the combustion zone, means for passing a fluid to be 45 heated, such as hydrocarbon oil, in a continuous stream, first through the fluid conduit-in the convection heating zone, then through the fluid conduit adjacent the-roof ofthe furnace, in a generaldirection counter-current to the. direction of firing'and general direction of flow of the combustion gases, and finally through the fluid conduit adjacent the floor of the combustion zone in' a general direction concurrent to the direction of firing and the general direction of flow of 55 the combustion'gases.
  • a fluid to be 45 heated such as hydrocarbon oil
  • '2 is a cross-sectional end elevation of the same furnace structure shown in Fig. 1.
  • the main furnace structure comprises side walls I and 2, end walls 3 and 4, a robf 5 and a floor 6.
  • a bridge wall I separates combustion zone 8 from the convection heating zone 9.
  • One or preferably a plurality of similar firing 15 tunnels one of which is indicated at It in Fig.
  • Air ducts H and II are provided, in the case illustrated, above and beneath firing tunnel of introducing additional air 8 in controlled quantities regto combustion zone I2 and II.
  • Fuel of any suitulated by dampers able type such as oil, gas or pulverized solid fuel is supplied by means of any suitable type of bumerinot shown) to firing tunnel Ill and a 25 of the air required for combustion is also supplied through tunnel It.
  • a regulated portion of the air required for combustion, as well as any amount of excess air desired may be supplied to combustion zone 8 through air ducts II and H and may be proportioned, as desired, between the air ducts located, respectively, above and below firing tunnel Ill.
  • a fluid conduit 13 comprising, in the case here illustrated, a plurality of horizontally disposed tubular elements l4 arranged in superimposed, horizontally parallel rows, is located within the convection heating zone 9 and is supplied with 40 convection heat from the combustion gases which pass from combustion zone 8, over bridge wall I, downward through convection zone 9 and. out of the furnace through flue l5 to a suitable stack (not shown).
  • Another fluid conduit l6 comprising, in the case here illustrated, a single horizontal row of elements I4 is located adjacent the roof of the furnace and is supplied with radiant heat from the flames and refractory walls of the furnace as well as with convection heat from the hot combustion gases.
  • Another fluid conduit I'I located along the floor of the combustion zone comprises, in the case illustrated, a single horizontal row of horizontally disposed tubular elements I 4 which are supplied with radiant heat from the flames and hot refractory walls of the furnace, as well as, when desired, with convection heat (of variable magnitude) from the hot combustion gases.
  • Fluid con-' duit It may serve, for example, when the furnace is utilized for the conversion of hydrocarbon oils, as a steam generating or superheating coil or as a means of reboiling reflux condensate from the fractionator of the cracking system or for any other desired purpose. It serves, in any case, as a means of recovering additional heat from the furnace gases, prior to their passage through flue It to the stack but is neither an essential nor novel featureof the present invention.
  • adjacent tubes in each row of fluid conduit I3 and the adjacent rows of this tube bank as well as adjacent tubes in each of the fluid conduits I6 and I! are connected in series by means of return bends or headers I9 located at the ends of the tubes outside the heating zone, as indicated in Fig. 2 of the drawing.
  • return bend connections on the near ends of adjacent tubes are indicated by the lines I9.
  • the tubes of fluid conduit I8 are also connected in the same manner, in the particular case here illustrated.
  • the oil flows through tube banks or fluid conduits I3, I6 and IT in the order named although, when desired, the flow may be in sequence through banks I3, I1 and I6.
  • the oil passes through bank I3 in a general direction counter-current to the general direction of travel of the combustion gases through this zone and is then transferred, as indicated by line 20, to the tube of bank I6 nearest end wall 4 of the furnace.
  • the oil then passes through bank IS in a general direction counter-current to the general direction of the flow of the combustion gases and the direction of firing, passing from the end tube in bank I6 adjacent end wall 3 of the furnace, as indicated by line 2
  • the oil passes through tube bank I! in a general direction concurrent to the general direction of firing and finally emerges from the end tube of bank I! nearest bridge wall I, from which it is discharged to subsequent portions of the cracking system (not shown).
  • tube bank I6 indicated in the drawing as I6, which is immediately above tube bank I3, in which case the oil is transferred directly from tube bank I3 to tube bank I6.
  • this arrangement is employed a somewhat higher rate of heating will ordinarily be obtained in tube bank I3, due to a somewhat higher combustion gas temperature in convection heating zone 9 brought about by the elimination of the cooling surface indicated at I6.
  • a considerable quantity of additional radiant heat from the roof of the furnace will be imparted particularly to the upper two or three rows of tubes in bank I3 and, when desired, section I6 of the fluid conduit may be replaced by one or more additional rows of tubes at the top of bank I3.
  • the degree of combustion obtained in firing tunnel I I! is controlled by the distribution of the air supplied to the furnace.
  • all of the air necessary for combustion is supplied through tunnel Ill, together with the fuel, all or the major portion of the combustion process will be completed in the firing tunnel and only a relatively short flame will extend from the mouth of the tunnel into combustion zone 8.
  • the same amount of total air is proportioned so that part of it is supplied through air ducts I I, appreciable combustion of the fuel will be accomplished in combustion zone 8 with a longer and more luminous flame in this zone.
  • Variation in the quantity of excess air supplied to the furnace serves to affect the furnace conditions in the usual manner. In this manner a control is obtained over the percentage of radiant heat, as compared to the total heat imparted to the fluid undergoing treatment, as well as over the distribution of radiant heat to different portions of the fluid conduit.
  • this natural tendency for the heat toconcentrate along the roof of the furnace may be augmented by supplying a large portion of the secondary air required for combustion and, when desired, a regulated amount of excess air and/or steam, through the air duct II' located beneath firing tunnel II] so that that portion of the fluid conduit located adjacent the floor of the furnace may be utilized as what is commonly termed a soaking section, wherein the fluid undergoing treatment may be maintained at or near the temperature attained in the previous portion of the fluid conduit without the addition of any appreciable amount of sensible heat.
  • oils of a relatively low boiling nature such as, for example, straight-run gasoline or other motor fuel or motor fuel fractions of inferior anti-knock value, naphtha, kerosene or kerosene distillate, pressure distillate bottoms and the like.
  • the jet action of the stream of combustion gases from the firing tunnel creates a zone of relatively low pressure beneath the flame and the stream of hot combustion gases near the point of exit of the gases from the firing tunnel, which, in the furnace shown, is in the zone occupied by a portion of tube bank I].
  • the inertia of the gases travelling toward bridge wall I produces, on the other hand a zone of relatively high pressure near the bridge wall.
  • baffle between tube bank it and bridge wall I may-be modified to suit requirements.
  • a solid baflle wall such as indicated in Figure 1 of the drawing, extending from the floor of the furnace to above the upper surface of the floor tubes, will practically eliminate the flow of gases-from the zone of high pressure adjacent the bridge wall to the zone of low pressure adjacent the firing tunnel.
  • a perforated baflle or a bailie wall extending, for example, to only the lower surface of the floor I I and careful measurements a substantially uniform from bridge wall I to the firing tunnels and by varying the size and spacing of the perforations and/or the height of the baflle wall the convection heat component supplied to tube bank l1 may be varied to suit requirements.
  • Conversion of hydrocarbonbils of relatively high-boiling nature is preferably carried out with increasing rates of heat input from the inlet to the outlet of tube bank l1, and, in such cases, baflle 22 is preferably omitted and the quantity of excess air supplied to the furnace as well as the method by which it is introduced into the combustion chamber is controlled, as previously described, so as to obtain higher average rates of decreasing rates of heat input towards the outlet.
  • the flowof gases under tube bank I1 is either restricted or eliminated byinstallation of a bafiie, such as indicated at 22 in Figure 1 of the drawing, inorder to restrict or eliminate the convection heat component which would otherwise be sup lied to tube bank H by this stream of gases.
  • a bafiie such as indicated at 22 in Figure 1 of the drawing
  • theamount of excess air supplied to the combustion zone and the manner in which it is supplied to this zone may be varied, as previously described-so as to obtain the desired rates of heat input in various portions of the fluid conduit, suitable for the type of oil undergoing treatment.
  • any desired type of heat- I treatment is obtainable by even whilethe process is inoperation, which may turned to the heating coil, the reaction space in i the reaction chamber, when operating on a nonresiduum basis, variations or intentional changes in the character of the charging stock and the like.
  • a furnace for the heating of fluids, having side walls, end walls, a roof and a floor, and a combustion and heating zone
  • a firing tunnel communicating with said combustion and heating zone, through which a parmixture is tially or completely burned fuel-air supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating Zone above and beneath the firing tunnel, a fluid conduit located adjacent the roof of the furnace, and a fluid conduit located adjacent the floor of the combustion and heating zone.
  • a furnace for the heating of fluids, having side walls, end walls, a roof and a floor, a combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion and heating zone between the firing tunnel and the bridge wall, means comprising a bave located between the last mentioned fluid conduit and the bridge wall for preventing the cyclic circulation of combustion gases beneath and through said fluid conduit and means for passing a stream of fluid to be heated through the fluid conduit in the order above mentioned.
  • a furnace for the heating of fluids, having side walls, end walls, a roof and a floor, a 1
  • combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately intro ducing regulated quantities of additional air to the combustion and heating zone above and be-.
  • a fluid conduit located in said separate heating zone neath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion and heating zone between the firing tunnel and the bridge wall, means comprising a bafile located between the lastmentioned fluid conduit and the bridge wall for restricting the cyclic circulation of combustion gases about said fluid conduit and meansfor passlng a stream oi fluid to be heated through the fluid conduits in "the order above mentioned.
  • a combustion and heating zone the combination of a firing tunnel communicating with said com bustion and heating zone, through which a partially or completely burned fuel-air mixture is,
  • meansv for separately introducing regulated quantities of additional air to combustion and heating zone above beneath the firing tunnel meansv for separately introducing regulated quantities of additional air to combustion and heating zone above beneath the firing tunnel, a fluid conduit located adjacent the roof of the turn-ace, a bridge wall, a fluid conduit located adjacent the floor oi the combustion zone between the firing ttumel and the bridge wall, and means comprising a baffle located between the last-mentioned conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through said lastmentioned conduit.
  • a firing tunnel communicating with said combustion and heating zone, through which a partially or completely burned -air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion zone between the firing tunnel and the bridge wall, means comprising a bame located between the last mentioned fluid conduit and the bridge wall for preventing or restricting the local circulation of combustion gases about said fluid conduit and means for passing the fluid to be heated first through the fluid conduit in said separate heating zone, in a general direction countercurrent to the general direction of the flow oi the combustion gases through this zone, then through the fluid conduit adjacent the roof of the furnace,
  • a furnace for the heating or" fluids, having side walls, end walls, a roof and a floor, and a combustion and heating zone, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the roof of the furnace, and a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the floor of the furnace.
  • a firing tunnel communicating with said oombustion and heating zone through which a par tially or completely burned fuel-air mixture is supplied thereto, means for separately introduc ing regulated quantities or" additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit comprising a plurality oi horizontal rows of horizontally dis posed tubular elements located within said separate heating zone, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the roof of the furnace, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the floor of the furnace between the firing tunnel and the bridge wall, means comprising a baffle located between the last mentioned fluid conduit and the bridge wall for preventing or restricting the local circulation of combustion gases about said fluid conduit, means for
  • An apparatus for heating fluids comprising a furnace having side walls, a roof and a floor, a bridge wall between the side walls extending upwardly from thefloor and terminating short of the roof, means for firing the furnace adjacent its lower portion through one of said side walls toward the bridge wall, means for introducing air to the furnace above and below the firing means, a fluid conduit adjacent the floor between the firing means and the bridge wall in a horizontal plane below the plane of the firing means, and means comprising a bame located between said conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through the conduit.
  • An apparatus for heating fluids comprising a furnace having side walls, a roof and a. floor, a
  • bridge wall between the sidewalls extending upwardly from the floor and terminating short of 7 firing the furnace adjacent its lower portion through one of said side walls toward the bridge wall, means for introducing air to the furnace above and below the firing means, a baflie of lesser height than the bridge wall extending upwardly from the, floor between the bridge wall and the firing means, a fluid conduit adjacent the floor between the firing means and the baflle in a horizontal plane below the plane of the firing means, a fluid conduit in the space between the bridge wall and the other of said side walls, and a fluid conduit adjacent the furnace roof having in the space defined by the bridge wall and the side wall through which the furnace is fired.
  • An apparatus for heating fiuids comprising a furnace having side walls, a rodf and a fioor, a firing tunnel projecting through one of the side walls above the floor, means for introducing air to the furnace above and below the firing tunnel, heating tubes adjacent the roof of the furnace, and additional heating tubes adjacent the floor of the furnace below the plane of the firing tunnel.
  • An apparatus for ing a furnace having side walls, a roof and a fioor, a bridge wall between the side walls extending upwardly from the floor and terminating short of the roof, means for firing the fur-' 'nace adiacent its lower portion through one of said side walls toward the bridge wall, a fiuid conduit adjacent the furnace fioor between the firing means and the bridge wall, and means comprising a baffle located between said conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through the conduit.
  • An apparatus for heating fluids comprising a furnace having side walls, a roof and a fioor, a bridge wall between the side walls extending upwardly from the floor and terminating short of the roof, a firing tunnel projecting through one of said-side walls into the lower portion of the furnace, a fluid conduit adjacent the floor below the plane of the firing tunnel and disposed between the last-mentioned-side wall and the bridge wall, and means comprising a baffle located between said conduit and the bridge wall for restricting local circulation of combustion gases about said conduit.

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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Description

Feb. 15, 1938. M K 7 2,108,687
HEATING OF FLUIDS Filed Oct. 24, 1953 HEM 6' TUNNEL b/n/scr/ols ZOA/E. FIG. I
B T T I? ETTTTTTTTTTTT'TT'T INVENTOR EV MEKLER BY ORNEY been possible in a 4o ments located adjacent the roof of the Patented Feb. 15. 1938 PATENT OFFICE HEATING OF FLUIDS Lev A. Mekler,
Oil Products Company, ration of Delaware This invention relates to an improved apparatus for the heating of fluids and more particularly refers to an improved form of furnace and heating method especially adapted for the heating' of hydrocarbon oils to the high temperatures required for their pyrolytic conversion. By use of the combination of features provided by the present invention a greater flexibility of operating conditions is obtained than has heretofore simple furnace structure of the general type disclosed. Flexibility of operation is an essential feature in cracking process furnaces, due to the wide variations and characteristics of different hydrocarbon oil cracking stocks. In the present invention this flexibility is attained in, a simple .furnace structure by a special arrangement of the fluid conduit and special flow of oil therethrough in combination with a method for controlling combustion,conditions in the furnace, particularly with respect to the length, luminosity and other characteristics of the flame produced.
One specific embodiment of the apparatus may, comprise a main furnace structure having end walls, side walls, a roof and a floor, a combustion zone within said furnace, means forsupplying a, combustible fuel-air mixture to the combustion zone, means for separately supplying controlled quantities of additional air to said combustion zone, a convection heating zone located within the furnace and separated from the combustion zone by a bridge wall, means for removing-combustion gases from said furnace through the convection heating zone, a fluid conduit comprising a plurality of horizontal rows of serially connected, horizontally disposed tubular elements located within said convectionheating zone, a fluid conduit comprising a horizontal row of serially connected, horizontally disposed tubular elefurnace,
a fluid conduit comprising a, horizontal row of seriallyconnected, horizontally disposed tubular elements located adjacent the floor of the combustion zone, means for passing a fluid to be 45 heated, such as hydrocarbon oil, in a continuous stream, first through the fluid conduit-in the convection heating zone, then through the fluid conduit adjacent the-roof ofthe furnace, in a generaldirection counter-current to the. direction of firing'and general direction of flow of the combustion gases, and finally through the fluid conduit adjacent the floor of the combustion zone in' a general direction concurrent to the direction of firing and the general direction of flow of 55 the combustion'gases.
' It for the purpose horizontally disposed tubular Chicago, 111., assignor to Universal Chicago, 111., a corpo- Appli'cation October 24, 1933, Serial No. 694,960 12 Claims. I (Cl. 122-356) The accompanying diagrammatic drawing 11- lustrates one form of apparatus embodying the features of the present invention and the process of the present invention will be more apparent with reference to the following description of 5 the drawing. Fig. 1 of the drawing is a crosssectional side elevation of the furnace, and Fig.
'2 is a cross-sectional end elevation of the same furnace structure shown in Fig. 1.
The main furnace structure comprises side walls I and 2, end walls 3 and 4, a robf 5 and a floor 6. Within the main furnace structure a bridge wall I separates combustion zone 8 from the convection heating zone 9.
One or preferably a plurality of similar firing 15 tunnels, one of which is indicated at It in Fig.
1, are provided for the introduction of a combustible fuel-air mixture into combustion zone 8. Air ducts H and II are provided, in the case illustrated, above and beneath firing tunnel of introducing additional air 8 in controlled quantities regto combustion zone I2 and II. Fuel of any suitulated by dampers able type such as oil, gas or pulverized solid fuel is supplied by means of any suitable type of bumerinot shown) to firing tunnel Ill and a 25 of the air required for combustion is also supplied through tunnel It. When desired, a regulated portion of the air required for combustion, as well as any amount of excess air desired, may be supplied to combustion zone 8 through air ducts II and H and may be proportioned, as desired, between the air ducts located, respectively, above and below firing tunnel Ill.
A fluid conduit 13 comprising, in the case here illustrated, a plurality of horizontally disposed tubular elements l4 arranged in superimposed, horizontally parallel rows, is located within the convection heating zone 9 and is supplied with 40 convection heat from the combustion gases which pass from combustion zone 8, over bridge wall I, downward through convection zone 9 and. out of the furnace through flue l5 to a suitable stack (not shown).
Another fluid conduit l6 comprising, in the case here illustrated, a single horizontal row of elements I4 is located adjacent the roof of the furnace and is supplied with radiant heat from the flames and refractory walls of the furnace as well as with convection heat from the hot combustion gases. Another fluid conduit I'I, located along the floor of the combustion zone comprises, in the case illustrated, a single horizontal row of horizontally disposed tubular elements I 4 which are supplied with radiant heat from the flames and hot refractory walls of the furnace, as well as, when desired, with convection heat (of variable magnitude) from the hot combustion gases.
Also in the particular case here illustrated .a separate fluid conduit i8, similar in construction to fluid conduit I3, is located beneath fluid con- ,duit I3 in convection heating zone 9. Fluid con-' duit It may serve, for example, when the furnace is utilized for the conversion of hydrocarbon oils, as a steam generating or superheating coil or as a means of reboiling reflux condensate from the fractionator of the cracking system or for any other desired purpose. It serves, in any case, as a means of recovering additional heat from the furnace gases, prior to their passage through flue It to the stack but is neither an essential nor novel featureof the present invention.
In the preferred embodiment of the invention, adjacent tubes in each row of fluid conduit I3 and the adjacent rows of this tube bank as well as adjacent tubes in each of the fluid conduits I6 and I! are connected in series by means of return bends or headers I9 located at the ends of the tubes outside the heating zone, as indicated in Fig. 2 of the drawing. In Fig. 1 these return bend connections on the near ends of adjacent tubes are indicated by the lines I9. The tubes of fluid conduit I8 are also connected in the same manner, in the particular case here illustrated. I
In the preferred embodiment of the invention, particularly as applied to the conversion'of hydrocarbon oils, the oil flows through tube banks or fluid conduits I3, I6 and IT in the order named although, when desired, the flow may be in sequence through banks I3, I1 and I6. Preferably, the oil passes through bank I3 in a general direction counter-current to the general direction of travel of the combustion gases through this zone and is then transferred, as indicated by line 20, to the tube of bank I6 nearest end wall 4 of the furnace. The oil then passes through bank IS in a general direction counter-current to the general direction of the flow of the combustion gases and the direction of firing, passing from the end tube in bank I6 adjacent end wall 3 of the furnace, as indicated by line 2|, to the tube at the same end of bank II. The oil passes through tube bank I! in a general direction concurrent to the general direction of firing and finally emerges from the end tube of bank I! nearest bridge wall I, from which it is discharged to subsequent portions of the cracking system (not shown).
It is within the scope of the invention, when desired, to eliminate that portion of tube bank I6, indicated in the drawing as I6, which is immediately above tube bank I3, in which case the oil is transferred directly from tube bank I3 to tube bank I6. When this arrangement is employed a somewhat higher rate of heating will ordinarily be obtained in tube bank I3, due to a somewhat higher combustion gas temperature in convection heating zone 9 brought about by the elimination of the cooling surface indicated at I6. Also, a considerable quantity of additional radiant heat from the roof of the furnace will be imparted particularly to the upper two or three rows of tubes in bank I3 and, when desired, section I6 of the fluid conduit may be replaced by one or more additional rows of tubes at the top of bank I3.
The degree of combustion obtained in firing tunnel I I! is controlled by the distribution of the air supplied to the furnace. When all of the air necessary for combustion is supplied through tunnel Ill, together with the fuel, all or the major portion of the combustion process will be completed in the firing tunnel and only a relatively short flame will extend from the mouth of the tunnel into combustion zone 8. When the same amount of total air is proportioned so that part of it is supplied through air ducts I I, appreciable combustion of the fuel will be accomplished in combustion zone 8 with a longer and more luminous flame in this zone. Variation in the quantity of excess air supplied to the furnace, whether supplied through firing tunnel Ill or ducts II, serves to affect the furnace conditions in the usual manner. In this manner a control is obtained over the percentage of radiant heat, as compared to the total heat imparted to the fluid undergoing treatment, as well as over the distribution of radiant heat to different portions of the fluid conduit.
By increasing the proportion of the air required for combustion supplied through air ducts I I, the amount of combustion in combustion zone 8 is increased and the proportion of radiant heat imparted to the fluid undergoing treatment may be increased. By firing with a greater proportion of the air required for combustion supplied through thefiring tunnel III, a shorter semiluminousflame is obtained and the proportion of radiant heat is decreased with a corresponding increase in the amount of convection heat supplied to the tubes of the fluid conduit and to the fluid undergoing treatment.
When it is desired to increase the heat absorption in that portion of the fluid conduit located adjacent the floor of the furnace, a large proportion of the secondary air used outside of tunnel I0 may be supplied through the air duct II, located above the firing tunnel. The relatively cold air thus admitted above the firing tunnel, being heavier than the products of combustion leaving tunnel I0, tends to blanket the flames and concentrate heat along the floor of the furnace. This is the reverse of the natural tendency of the flames and the heated gases to rise rapidly, causing a concentration of heat along the roof of the furnace, thereby supplying a large proportion of the total heat imparted to the oil as it passes through that portion of the fluid conduit located adjacent the roof of the furnace.
In the prese'ntinvention this natural tendency for the heat toconcentrate along the roof of the furnace may be augmented by supplying a large portion of the secondary air required for combustion and, when desired, a regulated amount of excess air and/or steam, through the air duct II' located beneath firing tunnel II] so that that portion of the fluid conduit located adjacent the floor of the furnace may be utilized as what is commonly termed a soaking section, wherein the fluid undergoing treatment may be maintained at or near the temperature attained in the previous portion of the fluid conduit without the addition of any appreciable amount of sensible heat. This is particularly desirable in the treatment of oils of a relatively low boiling nature such as, for example, straight-run gasoline or other motor fuel or motor fuel fractions of inferior anti-knock value, naphtha, kerosene or kerosene distillate, pressure distillate bottoms and the like.
On the other hand, it is ordinarily desirable, in the conversion of oils of a relatively high boiltubes will only partially block the flow of gases I ing nature such as residual oils, fuel oil, topped crude and in some cases intermediate oil such as gas oil and the like, to avoid maintaining the oil at the maximum conversion temperature attained for any considerable length of time but to maintain a fairly constant increase in temperature (rate of sensible heat input) throughout the entire path of travel of the oil through the fluid conduit. This is accomplished in the present invention, in the manner previously indicated, by properly proportioning the total air required for combustion between firing tunnel Ill and air ducts II and by regulation of the proportion of secondary air supplied, respectively, through the upper and lower air ducts ll.
As a further feature of the present invention additional means are provided for controlling the heat input relationship between tube bank I'I, adjacent the floor of the furnace and tube bank l6 adjacent to the roof. This is accomplished by the installation or omission of a baiile 22 between tube bank l1 and bridge wall I.
In the operation of a furnace, such as illustrated, the jet action of the stream of combustion gases from the firing tunnel creates a zone of relatively low pressure beneath the flame and the stream of hot combustion gases near the point of exit of the gases from the firing tunnel, which, in the furnace shown, is in the zone occupied by a portion of tube bank I]. The inertia of the gases travelling toward bridge wall I produces, on the other hand a zone of relatively high pressure near the bridge wall. As a result there is a considerable flow of gases, countercurrent to the general direction of firing and the flow of the main body of the gases, from the bridge wall toward the firing tunnels between the tubes of bank I! and the floor of the fur-' nace and a considerable amount of convection heat is imparted to the. tubes of bank H, which are sweptby this flow of gases, in addition to the radiant heat component supplied to the tubes of bank H from the flames, the main bodyof gases and the hot refractories of the furnace. This materially increases the overall rate of heat input in tube. bank of oil and furnace temperatures indicate that an increasing rate of heat input is obtained from the inlet to the outlet of tube bank ll (i. e. from the portion of this bank'adjacent theflring tunnel to the portion adjacent the bridge wall),
' because of this flow.
When the flow of gases beneath the floor tubes from the zone of high pressure to the zone of low pressure is either restricted or eliminated the furnace is operated by installing a baiile 22 between tube bank I! and bridge wail I whereby the convection component of heat input into bank H is reduced or completely eliminated. This results in a lower overall rate of heat input to tube bank W and in or decreasing rate of.heat input from the inlet to the outlet of this bank.
The efiect of the baffle between tube bank it and bridge wall I may-be modified to suit requirements. by altering the form or type of baffle employed, for example, a solid baflle wall such as indicated in Figure 1 of the drawing, extending from the floor of the furnace to above the upper surface of the floor tubes, will practically eliminate the flow of gases-from the zone of high pressure adjacent the bridge wall to the zone of low pressure adjacent the firing tunnel. A perforated baflle or a bailie wall extending, for example, to only the lower surface of the floor I I and careful measurements a substantially uniform from bridge wall I to the firing tunnels and by varying the size and spacing of the perforations and/or the height of the baflle wall the convection heat component supplied to tube bank l1 may be varied to suit requirements.
Conversion of hydrocarbonbils of relatively high-boiling nature is preferably carried out with increasing rates of heat input from the inlet to the outlet of tube bank l1, and, in such cases, baflle 22 is preferably omitted and the quantity of excess air supplied to the furnace as well as the method by which it is introduced into the combustion chamber is controlled, as previously described, so as to obtain higher average rates of decreasing rates of heat input towards the outlet.
of the coil, the flowof gases under tube bank I1 is either restricted or eliminated byinstallation of a bafiie, such as indicated at 22 in Figure 1 of the drawing, inorder to restrict or eliminate the convection heat component which would otherwise be sup lied to tube bank H by this stream of gases. Also theamount of excess air supplied to the combustion zone and the manner in which it is supplied to this zone may be varied, as previously described-so as to obtain the desired rates of heat input in various portions of the fluid conduit, suitable for the type of oil undergoing treatment.
Particular attention is directed to the cooperative relation between the use of a. baffie between the bank of floor tubes and the bridge wall of the furnace and the methods,- previously dethe inlet to the outlet of scribed, for controllingconibustion conditions in the furnace.
It will be apparent from the foregoing that in the present invention ing curve, regulated to suit the of oil undergoing virtue of the cooperative nature of the arrangement of fluid conduits illustrated and described, the path of flow of the oil therethrough and regulation of the firing conditions as herein disclosed. This is accomplished in the present invention without any change in the arrangement of the fluid conduits for oils of difierent charac-. teristics and even without .any change in the direction and path of flow of the oil through the fluid conduit. It is thus possible, when desired, to change the type of heating curve employed particular type any desired type of heat- I treatment, is obtainable by even whilethe process is inoperation, which may turned to the heating coil, the reaction space in i the reaction chamber, when operating on a nonresiduum basis, variations or intentional changes in the character of the charging stock and the like.
I claim as my invention:
1. In a furnace, for the heating of fluids, having side walls, end walls, a roof and a floor, and a combustion and heating zone, the combination of'a firing tunnel communicating with said combustion and heating zone, through which a parmixture is tially or completely burned fuel-air supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating Zone above and beneath the firing tunnel, a fluid conduit located adjacent the roof of the furnace, and a fluid conduit located adjacent the floor of the combustion and heating zone.
2. In a furnace, for the heating of fluids, having side walls, end walls, a roof and a floor, a combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion and heating zone between the firing tunnel and the bridge wall, means comprising a baiile located between the last mentioned fluid conduit and the bridge wall for preventing the cyclic circulation of combustion gases beneath and through said fluid conduit and means for passing a stream of fluid to be heated through the fluid conduit in the order above mentioned.
3. In a furnace, for the heating of fluids, having side walls, end walls, a roof and a floor, a 1
combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately intro ducing regulated quantities of additional air to the combustion and heating zone above and be-. neath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion and heating zone between the firing tunnel and the bridge wall, means comprising a bafile located between the lastmentioned fluid conduit and the bridge wall for restricting the cyclic circulation of combustion gases about said fluid conduit and meansfor passlng a stream oi fluid to be heated through the fluid conduits in "the order above mentioned.
i. In a furnace, for the heating of fluids, haw ing side walls, end Walls, a roof and a floor, and
a combustion and heating zone, the combination of a firing tunnel communicating with said com bustion and heating zone, through which a partially or completely burned fuel-air mixture is,
supplied, thereto, meansv for separately introducing regulated quantities of additional air to combustion and heating zone above beneath the firing tunnel, a fluid conduit located adjacent the roof of the turn-ace, a bridge wall, a fluid conduit located adjacent the floor oi the combustion zone between the firing ttumel and the bridge wall, and means comprising a baffle located between the last-mentioned conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through said lastmentioned conduit.
5. In a furnace, for the heating of fluids, hav= ing sidewalls, end walls, a roof and a floor, a combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination of a firing tunnel communicating with said combustion and heating zone, through which a partially or completely burned -air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit located in said separate heating zone, a fluid conduit located adjacent the roof of the furnace, a fluid conduit located adjacent the floor of the combustion zone between the firing tunnel and the bridge wall, means comprising a bame located between the last mentioned fluid conduit and the bridge wall for preventing or restricting the local circulation of combustion gases about said fluid conduit and means for passing the fluid to be heated first through the fluid conduit in said separate heating zone, in a general direction countercurrent to the general direction of the flow oi the combustion gases through this zone, then through the fluid conduit adjacent the roof of the furnace, in a general direction counter-current to the general direction of the firing, then through the fluid conduit adjacent the floor oi the combustion zone, in a general direction concurrent to the direction of firing, and finally out of the furnace.
' 6. in a furnace, for the heating or" fluids, hav ing side walls, end walls, a roof and a floor, and a combustion and heating zone, the combination of a firing tunnel communicating with said combustion and heating zone through which a partially or completely burned fuel-air mixture is supplied thereto, means for separately introducing regulated quantities of additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the roof of the furnace, and a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the floor of the furnace.
7. In a furnace, for the heating of fluids, having side walls, end walls, a roof and a floor, a combustion and heating zone and a separate heating zone supplied with combustion gases from the combustion and heating zone and separated therefrom by a bridge wall, the combination or" a firing tunnel communicating with said oombustion and heating zone through which a par tially or completely burned fuel-air mixture is supplied thereto, means for separately introduc ing regulated quantities or" additional air to the combustion and heating zone above and beneath the firing tunnel, a fluid conduit comprising a plurality oi horizontal rows of horizontally dis posed tubular elements located within said separate heating zone, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the roof of the furnace, a fluid conduit comprising a single horizontal row of horizontally disposed tubular elements located adjacent the floor of the furnace between the firing tunnel and the bridge wall, means comprising a baffle located between the last mentioned fluid conduit and the bridge wall for preventing or restricting the local circulation of combustion gases about said fluid conduit, means for passing the fluid to be heated first in series through adjacent tubes in each row of the fluid conduit located in said separate heating zone and through the adjacent rows of this fluid earn duit in series, in a general direction counter-current to the general direction of flow of the combustion gases through this zone, then in series through adjacent tubes in the fiuid conduit located adjacent the roof of the furnace, in a general direction counter-current to the general direction of firing, then in series through adjacent tubes in the fluid conduit located adjacent the floor of the combustion and heating zone, in a general direction concurrent to the general direction of firing, and finally out of the furnace.
8. An apparatus for heating fluids comprising a furnace having side walls, a roof and a floor, a bridge wall between the side walls extending upwardly from thefloor and terminating short of the roof, means for firing the furnace adjacent its lower portion through one of said side walls toward the bridge wall, means for introducing air to the furnace above and below the firing means, a fluid conduit adjacent the floor between the firing means and the bridge wall in a horizontal plane below the plane of the firing means, and means comprising a bame located between said conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through the conduit.
9. An apparatus for heating fluids comprising a furnace having side walls, a roof and a. floor, a
bridge wall between the sidewalls extending upwardly from the floor and terminating short of 7 firing the furnace adjacent its lower portion through one of said side walls toward the bridge wall, means for introducing air to the furnace above and below the firing means, a baflie of lesser height than the bridge wall extending upwardly from the, floor between the bridge wall and the firing means, a fluid conduit adjacent the floor between the firing means and the baflle in a horizontal plane below the plane of the firing means, a fluid conduit in the space between the bridge wall and the other of said side walls, and a fluid conduit adjacent the furnace roof having in the space defined by the bridge wall and the side wall through which the furnace is fired.
10. An apparatus for heating fiuids comprising a furnace having side walls, a rodf and a fioor, a firing tunnel projecting through one of the side walls above the floor, means for introducing air to the furnace above and below the firing tunnel, heating tubes adjacent the roof of the furnace, and additional heating tubes adjacent the floor of the furnace below the plane of the firing tunnel.
11. An apparatus for ing a furnace having side walls, a roof and a fioor, a bridge wall between the side walls extending upwardly from the floor and terminating short of the roof, means for firing the fur-' 'nace adiacent its lower portion through one of said side walls toward the bridge wall, a fiuid conduit adjacent the furnace fioor between the firing means and the bridge wall, and means comprising a baffle located between said conduit and the bridge wall for preventing cyclic circulation of combustion gases beneath and through the conduit.
12. An apparatus for heating fluids comprising a furnace having side walls, a roof and a fioor, a bridge wall between the side walls extending upwardly from the floor and terminating short of the roof, a firing tunnel projecting through one of said-side walls into the lower portion of the furnace, a fluid conduit adjacent the floor below the plane of the firing tunnel and disposed between the last-mentioned-side wall and the bridge wall, and means comprising a baffle located between said conduit and the bridge wall for restricting local circulation of combustion gases about said conduit.
fLEv A.IMEKLER.
at least a portion thereof heating fluids compris-
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2848383A (en) * 1954-10-20 1958-08-19 Exxon Research Engineering Co Method and apparatus for heating hydrocarbon fluids

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2848383A (en) * 1954-10-20 1958-08-19 Exxon Research Engineering Co Method and apparatus for heating hydrocarbon fluids

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