US3924574A

US3924574A - Fluid heater apparatus

Info

Publication number: US3924574A
Application number: US560821A
Authority: US
Inventors: Harold O Ebeling
Original assignee: Black Sivalls and Bryson Inc
Current assignee: Black Sivalls and Bryson Inc
Priority date: 1975-03-21
Filing date: 1975-03-21
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09
Also published as: BE835240A; JPS51110743A; NO753604L; GB1487455A; SE7512280L; FR2304871A1; NL7513086A; DE2548540B2; ATA841975A; NO139706C; NO139706B; AU8605075A; DE2548540A1; IT1045590B; DE2548540C3; ZA756749B; BR7507274A

Abstract

The present invention relates to fluid heater apparatus having a firing wall, a back wall and side walls defining a furnace space. A plurality of fluid heating tubes are disposed in the furnace space and one or more high intensity combustion burners are attached to the firing wall and positioned so that combustion gases produced thereby are directed into the furnace space and caused to circulate around the heating tubes. By the present invention at least one baffle is disposed in the furnace space adjacent to the firing wall defining a secondary chamber in which additional heating tubes are disposed so that combustion gases impinge on the baffle after impinging on the back wall and are caused to recirculate around the heating tubes and then flow through the secondary chamber whereby additional heat is transferred to the fluid being heated.

Description

United States Patent Ebeling Inventor:

Assignee:

Filed:

Appl. No.2

FLUID HEATER APPARATUS Harold O. Ebeling, Tulsa, Okla.

Black, Sivalls & Bryson, Inc.,

Houston, Tex.

Mar. 21, 1975 US. Cl 122/23; 110/49 R; 122/356;

References Cited UNITED STATES PATENTS Kemp 122/356 X Thurley 122/23 Zenlner, Jr. et al. 122/356 Ebeling et al 122/356 Dec. 9, 1975 [57] ABSTRACT The present invention relates to fluid heater apparatus having a firing wall, a back wall and side walls defining a furnace space. A plurality of fluid heating tubes are disposed in the furnace space and one or more high intensity combustion burners are attached to the firing wall and positioned so that combustion gases produced thereby are directed into the furnace space and caused to circulate around the heating tubes. By the present invention at least one baffle is disposed in the furnace space adjacent to the firing wall defining a secondary chamber in which additional heating tubes are disposed so that combustion gases impinge on the baffle after impinging on the back wall and are caused to recirculate around the heating tubes and then flow through the secondary chamber whereby additional heat is transferred to the fluid being heated.

9 Claims, 6 Drawing Figures U.S. Patent Dec. 9, 1975 Sheet 1 of 3 3,924,574

US. Patent Dec. 9, 1975 Sheet 2 of3 3,924,574

FUEL 6145 US. Patent Dec. 9, 1975 Sheet 3 of3 3,924,574

FUEL GA 5 IF IF 1, J

FLUID HEATER APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to improved fluid heater apparatus, and more particularly, but not by way of limitation, to improved heater apparatus of the type wherein hot combustion gases are caused to circulate around heating tubes disposed within a furnace space.

2. Description of the Prior Art A great variety of fluid heater apparatus have been developed and used successfully. One such heater which has proven to be particularly useful in the oil chemical and other industries for heating vrious types of fluids is described and claimed in U.S. Pat. No. 2,993,479, assigned to the assignee of this present invention. This type of heater is basically comprised of a wall structure forming a furnace space which contains a plurality of heating tubes and one or more high intensity combustion burners are connected to a wall of the furnace space. High intensity combustion burners are characterized in that substantially complete combustion takes place within the combustion chambers of the burners, and as a result, the burners can be mounted in direct communication with the furnace space. An air blower is utilized with the burners so that the products of combustion formed by the burners are directed into the furnace space under super-atmospheric pressure and caused to be circulated around the heating tubes therein in a manner such that even connection heating of the tubes and the fluid passing therethrough results.

By the present invention an improved fluid heater apparatus of the type described above is provided whereby greater recirculation of the combustion gases within the furnace space and around the heating tubes results and a secondary chamber is provided in the furnace space containing heating tubes over which the combustion gases flow thereby transferring additional heat from the combustion gases to the fluid being heated.

SUMMARY OF THE INVENTION The present invention relates to an improved heater apparatus comprising a firing wall, a back wall and side walls defining a furnace space. A plurality of fluid heating tubes are disposed in the furnace space and one or more high intensity combustion burners are attached to the firing wall and positioned so that combustion gases produced by the burners are directed into the furnace space. The combustion gases impinge on the back wall of the furnace space and circulate around the heating tubes. At least one baffle is disposed in the furnace space adjacent to the firing wall defining a secondary chamber therewithin between the firing wall and the baffle so that at least a portion of the combustion gases produced by the burners impinge on the baffle after impinging on the back wall and are caused to recirculate around the heating tubes. At least one stack is attached to a side wall of the furnace space communicated with the secondary chamber so that combustion gases are withdrawn from the furnace space through the secondary chamber.

It is, therefore, a general object of the present invention to provide an improved fluid heater apparatus.

A further object of the present invention is the provision of an improved fluid heater apparatus of the type 2 wherein combustion gases are circulated within a furnace space whereby maximum utilization of the heat content of the combustion gases is realized.

Yet a further object of the present invention is the provision of an improved heater apparatus wherein increased recirculation of combustion gases around the heating tubes results.

Still another object of the present invention is the provision of an improved heater apparatus including a secondary chamber within the furnace space having fluid heating tubes disposed therein whereby heat contained in the combustion gases normally lost to the stack is transferred to the fluid being heated.

Other and further objects of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows when taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view partly in section, of one form of the improved heater apparatus of the present invention.

FIG. 2 is a front elevational view of the heater apparatus of FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a front elevational view taken in cross-section of an alternate form of the improved heater apparatus of the present invention.

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, and particularly to FIGS. 1 through 4, the improved fluid heater apparatus of the present invention is illustrated and generally designated by the numeral 10. The apparatus 10 is basically comprised of a rectangular firing wall 12, a rectangular back wall 14 and four rectangular side walls 16 forming a furnace space 18. A plurality offluid heating tubes 20 are disposed within the furnace space 18 connected together in a conventional manner by return bends 22. As best shown in FIGS. 3 and 4, the heating tubes 20 are preferably divided into a pair of

tube banks

25 and 27 positioned on opposite sides of the furnace space 18 so that a space free of heating tubes is provided between the firing wall 12 and back wall 14 of the furnace space 18. Each of the

tube banks

25 and 27 includes an inlet connection 24 and an outlet connection 26 passing through one of the side walls 16 of the furnace space 18.

The heating tubes 20 are positioned within the furnace space 18 parallel to each other and parallel to two opposite side walls 16 ofthe furnace space 18. A pair of high intensity combustion burners 30 are attached to the firing wall 12 positioned on a line intermediate to the side walls 16 which are parallel to the heating tubes 20. The term high intensity combustion burner is used herein to mean any burner apparatus or burner apparatus in combination with one or more air or com bustion gas blowers which is capable of producing hot combustion gases at a relatively high velocity under super-atmospheric pressure. A particularly suitable type of high intensity combustion burner which is preferred for use in accordance with the present invention 3 is described and claimed in US. Pat. No. 3,265,113, assigned to the assignee of this invention.

Each of the high intensity combustion burners 30 includes a combustion air inlet 32 connected to a source of combustion air at super-atmospheric pressure such as an atmospheric air blower (not shown), and includes a fuel gas inlet 34 connected to a source of fuel gas. Conventional instruments and controls (not shown) are provided in association with the burners 30 so that fuel and combustion air are supplied to the burners 30 in a substantially stoichiometric mixture. Substantially complete combustion of the mixture takes place within the burners 30 thereby producing relatively high velocity jets of hot combustion gases which are discharged by the burners 30 into the furnace space 18 in a direction towards the back wall 14 thereof.

A pair of baffles 36 are disposed within the furnace space 18 adjacent the firing wall positioned in a plane parallel thereto. Each of the baffles 36 is rectangular in shape and is sealingly attached, such as by welding, at one side and the ends thereof to the side walls 16 forming the furnace space 18. In addition, the baffles 36 are positioned on opposite sides of the burners 30 and are of a size such that the inward sides of the baffles 36 terminate short of a line intermediate to the side walls 16 which are parallel to the heating tubes 20 thereby forming a rectangular opening running the length of the furnace space 18 above the burners 30.

The baffles 36 form a pair of secondary chambers 38 between the firing wall 12 and the baffles 36 on opposite sides of the burners 30. The lower portions of the tube banks and 27 are disposed within the chambers 38 as best shown in FIG. 3. A pair of stacks 40 for withdrawing spent combustion gases from the furnace space 18 are attached to each of the side walls 16 which are parallel to the heating tubes 20 by way of connections 42 disposed therein. The connections 42 communicate with the secondary chambers 38 so that combustion gases withdrawn from the furnace space 18 are caused to flow through the chambers 58.

A pair of elongated concave-convex baffles 44 are disposed within the furnace space 18 and positioned with the concave surfaces thereof facing the heating tubes 20. The baffles 44 are attached to the side walls 16 which are parallel to the heating tubes 20 and to the upper sides of the baffles 36 in a conventional manner such as by welding. As will be understood, the

baffles

36 and 44 on each side of the burners can be integrally formed from single metal plates, or a plurality of metal plates can be used as dictated by good manufacturing techniques.

Referring now to FIGS. 5 and 6, an alternate form of the improved fluid heater apparatus of the present invention is illustrated and generally designated by the numeral 50. The apparatus 50 is similar to the apparatus 10 described above, except that the firing wall 52 and the back wall 54 are of circular shape and the side walls are formed of a single cylindrical wall 56 thereby forming a cylindrical furnace space 58.

A plurality of circular heating tubes 60 are disposed within the furnace space 58 connected together in a conventional manner to form a pair of helical coils connected in series and having an inlet connection 62 passing through the side wall 56 and an outlet connection 64 passing through the back wall 54. A continuous annular baffle 66 is disposed within the furnace space 58 adjacent to the firing wall 52 in a plane parallel thereto. The baffle 66 is attached at its outer sides to the cylindrical wall 56 such as by welding. A high intensity combustion burner 68 of the type described above is attached to the firing wall 52 at a central position therein so that the opening in the annular baffle 66 is positioned above the discharge of the burner 68. The annular baffle 66 forms a secondary chamber 69 between it and the firing wall 52 within the furnace space 58, and four stacks 70 are connected to the cylindrical side wall 56 by way of connections 72 communicating with the secondary chamber 69.

Preferably, the heating tubes 60 are of a diameter and arranged in a manner so that in cross section, as shown in FIG. 5, the heating tubes are stacked vertically above the annular baffle 66 and a space free of heating tubes is provided between the firing wall 52 and burner 68 and the back wall 54 of the furnace space 58. Several of the heating tubes 60 are disposed within the secondary chamber 69 formed by the baffle 66.

An annular concave-convex baffle 76 is provided positioned with the concave surface thereof facing the heating tubes 60 and attached to the side wall 56 and the top side of the annular baffle 66.

OPERATION In operation of the improved fluid heating apparatus 10 illustrated in FIGS. 1 through 4, relatively high velocity jets of hot combustion gases generated by the burners 30 are directed into the furnace space 18 from the firing wall 12 towards the back wall 14 thereof. The jets of combustion gases impinge against the back wall 14 and circulate around the heating tubes 20 as shown by the arrows in FIG. 3. After impinging on the back wall 14 the combustion gases flow around the heating tubes 20 in a generally downward direction towards the

baffles

44 and 36, and at least a portion of the combustion gases impinge on the

baffles

44 and 36 causing them to recirculate around the heating tubes 20 in a generally upward direction. The combustion gases then change direction and travel downwardly through the space between the baffles 36 and through the secondary chambers 38 wherein they flow over the heating tubes 20 disposed therein. As will be understood, as the combustion gases circulate around the heating tubes 20 positioned above the baffles 36 heat is transferred from the combustion gases to the fluid being heated. Because the combustion gases are caused to circulate and recirculate around the heating tubes, substantially even heating thereof takes place resulting in highly efficient heat transfer from the combustion gases to the fluid being heated. The combustion gases flowing through the chambers 38 flow over and around the heating tubes 20 disposed therein giving up additional heat to the fluid being heated. The spent combustion gases are then withdrawn from the chambers 38 and the furnace space 38 by way of the stacks 40 connected thereto.

The concave-convex baffles 44 disposed in the furnace space 18 facilitate the smooth change in direction of the combustion gases traveling downwardly and impinging thereon increasing the recirculation of the gases around the heating tubes 20.

The operation of the improved fluid heating apparatus 50 illustrated in FIGS. 5 and 6 is similar to that described above for the apparatus 10. That is, a high velocity jet of combustion gases is generated by the burner 68 and directed from the firing wall 52 towards the back wall 54 of the furnace space 58 as shown by the arrows in FIG. 3. The combustion gases impinge against the back wall 54 and circulate around the heating tubes 60 in a generally downward direction within the furnace space 58. Afterimpinging on the back wall 54 at least a portion of the combustion gases impinge on the

baffles

66 and 76 and are caused to recirculate around'the heating tubes 60 in a generally upward direction. Theh combustion gases then change direction and flow downwardly around the inner side of the annular baffle 66and over and around the heating tubes 60 disposed in the chamber 69 formed thereby. As the combustion gases flow through the secondary chamber 69, heat is given up to the fluid being heated flowing within the heating tubes disposed therein and the resultant spent combustion gases are withdrawn from the chamber 69 and the furnace space 58 by way of the stacks 70 attached thereto. The concave-convex baffle 76 facilitates the smooth change in direction of the combustion gases impinging thereon increasing the recirculation of the gases around the heating tubes 60.

The combination of increased circulation of combustion gases around the heating tubes disposed within the furnace space of the improved heater apparatus of this invention and the additional heat transferred from the combustion gases as they pass through the secondary chamber or chambers provided in the furnace space bring about a fluid heater apparatus of high heat transfer efficiency.

As will be understood by those skilled in the art, the heating tubes disposed within the furnace space of the apparatus can be connected in parallel banks, in series or in other flow arrangements as dictated by the conditions of the fluid to be heated and the heat required to be transferred thereto. In addition, any number of high intensity combustion burners can be utilized as dictated by the heat release required, etc. Further, more or less stacks than those disclosed can be utilized, and combustion gases can be circulated from adjacent the back wall within the furnace space to a point adjacent the firing wall thereof externally of the furnace space through the use of conduit means and a combustion gas blower.

Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those inherent therein. While presently preferred embodiments of the invention have been described for the purpose of disclosure numerous changes in the details of construction and arrangement of parts can be made which will readily suggest themselves to those skilled in the art. For example, as disclosed, the furnace space of the heater apparatus can be square, rectangular or cylindrical in shape and the heating tubes can be straight, circular, formed into continuous helical coils, etc. Such arrangements are encompassed within the spirit of the invention disclosed herein and the scope of the appended claims.

What is claimed is:

1. In a fluid heater apparatus having a firing wall, a back wall and side walls defining a furnace space, a plurality of fluid heating tubes disposed in said furnace space and one or more high intensity combustion burners attached to said firing wall and positioned so that combustion gases produced by the burners are directed into said furnace space, impinge on said back wall and are caused to circulate around said heating tubes thereby bringing about the transfer of heat from said combustion gases to the fluid being heated, the improvement which comprises:

at least one baffle disposed in said furnace space adjacent to said firing wall defining a secondary chamber within said furnace space between said firing wall and said baffle so that at least a portion of said combustion gases produced by said burner 'or burners impinge on said baffle after impinging on 'said back wall and are caused to recirculate 1 around said heating tubes; and v f at leastone stack attached to said walls defining said furnace space and communicating with said secondary chamber so that combustion gases are withdrawn from said furnace space through said secondary chamber.

2; The fluid heater apparatus of claim 1 which is further characterized to include a plurality of fluid heating tubes disposed within said secondary chamber so that combustion gases flowing therethrough flow over and around said heating tubes thereby bringing about the transfer of additional heat from said combustion gases to said fluid being heated.

3. The fluid heater apparatus of claim 2 which is further characterized to include rectangular walls defining said furnace space with the axes of said heating tubes being parallel to each other and to two opposite side walls of said furnace space.

4. The fluid heater apparatus of claim 3 wherein said burner or burners are positioned on a line intermediate to said side walls which are parallel to said heating tubes and said baffle is further characterized to be comprised of a pair of flat plates sealingly attached to said side walls on opposite sides of said line on which said burner or burners are positioned thereby defining a pair of secondary chambers on opposite sides of said burner or burners.

5. The fluid heater apparatus of claim 4 which is further characterized to include a pair of stacks attached to each of said side walls and communicating with said secondary chambers so that combustion gases are withdrawn from said furnace space through said secondary chambers.

6. The fluid heater apparatus of claim 2 wherein said firing wall and back wall are circular in shape, said side walls form a cylindrical enclosure thereby defining a cylindrical furnace space, said parallel heating tubes are circular in shape and said baffle is annular in shape.

7. In a fluid heater apparatus having a rectangular firing wall, a rectangular back wall and rectangular side walls defining a furnace space, a plurality of parallel fluid heating tubesdisposed within said furnace space positioned parallel to two opposite sides of said furnace space and one or more high intensity combustion burners attached to said firing wall and positioned on a line intermediate to said opposite side walls of said furnace space parallel to said heating tubes whereby combustion gases produced by said burner or burners are directed into said furnace space, impinge on said back wall and are caused to circulate around said heating tubes thereby bringing about the transfer of heat from said combustion gases to the fluid being heated, the improvement which comprises:

a pair of baffles disposed in said furnace space adjacent to and in a plane parallel to said firing wall, each of said baffles being sealingly attached to one of said opposite side walls of said furnace space parallel to said heating tubes thereby defining a pair of secondary chambers on opposite sides of said burner or burners so that at least a portion of said combustion gases produced by said burner or flow over and around said heating tubes thereby bringing about the transfer of additional heat from said combustion gases to said fluid being heated.

9. The fluid heater apparatus of claim 8 wherein said fluid heating tubes are divided into two banks within said furnace space, said banks being positioned on opposite sides of said line on which said burner or burners are positioned thereby providing a space free of heating tubes between said burner or burners and said back wall whereby said combustion gases first impinge on said back wall and then circulate around said heating tubes.

Claims

1. In a fluid heater apparatus having a firing wall, a back wall and side walls defining a furnace space, a plurality of fluid heating tubes disposed in said furnace space and one or more high intensity combustion burners attached to said firing wall and positioned so that combustion gases produced by the burners are directed into said furnace space, impinge on said back wall and are caused to circulate around said heating tubes thereby bringing about the transfer of heat from said combustion gases to the fluid being heated, the improvement which comprises: at least one baffle disposed in said furnace space adjacent to said firing wall defining a secondary chamber within said furnace space between said firing wall and said baffle so that at least a portion of said combustion gases produced by said burner or burners impinge on said baffle after impinging on said back wall and are caused to recirculate around said heating tubes; and at least one stack attached to said walls defining said furnace space and communicating with said secondary chamber so that combustion gases are withdrawn from said furnace space through said secondary chamber.

2. The fluid heater apparatus of claim 1 which is further characterized to include a plurality of fluid heating tubes disposed within said secondary chamber so that combustion gases flowing therethrough flow over and around said heating tubes thereby bringing about the transfer of additional heat from said combustion gases to said fluid being heated.

7. In a fluid heater apparatus having a rectangular firing wall, a rectangular back wall and rectangular side walls defining a furnace space, a plurality of parallel fluid heating tubes disposed within said furnace space positioned parallel to two opposite sides of said furnace space and one or more high intensity combustion burners attached to said firing wall and positioned on a line intermediate to said opposite side walls of said furnace space parallel to said heating tubes whereby combustion gases produced by said burner or burners are directed into said furnace space, impinge on said back wall and are caused to circulate around said heating tubes thereby bringing about the transfer of heat from said combustion gases to the fluid being heated, the improvement which comprises: a pair of baffles disposed in said furnace space adjacent to and in a plane parallel to said firing wall, each of said baffles being sealingly attached to one of said opposite side walls of said furnace space parallel to said heating tubes thereby defining a pair of secondary chambers on opposite sides of said burner or burners so that at least a portion of said combustion gases produced by said burner or burners impinge on said baffles after impinging on said back wall and are caused to recirculate around said heating tubes; and a pair of stacks attached to each of said opposite side walls of said furnace space parallel to said heating tubes and communicating with said secondary chambers so that combustion gases are withdrawn from said furnace space through said secondary chambers.

8. The fluid heater apparatus of claim 7 which is further characterized to include a plurality of fluid heating tubes disposed in each of said secondary chambers so that combustion gases flowing therethrough flow over and around said heating tubes thereby bringing about the transfer of additional heat from said combustion gases to said fluid being heated.