US3652194A

US3652194A - Blue-flame liquid-fuel burner process, apparatus and utilization systems

Info

Publication number: US3652194A
Application number: US860662A
Authority: US
Inventors: Frank W Bailey
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-09-24
Filing date: 1969-09-24
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: CA921821A

Abstract

Blue-flame burner process, apparatus and utilization systems producing a quiet, stable, essentially sootless blue flame from liquid fuel, particularly hydrocarbon fuels, fuel oil and the like and producing substantially complete combustion of the fuel, being more efficient than conventional oil burners and eliminating particulate matter in the exhaust products, contributing to substantially reduced air pollution and additionally providing more efficient utilization of the heat generated. In the blue-flame process the kinetics of combustion are controlled by close and effective coupling to a heat sink, and novel close coupling systems with higher performance heat exchangers are provided. Compact, lightweight inexpensive burner units are provided which are adapted to be constructed with a generally rectangular J-shaped configuration adapted for close coupling to a planar area of a heat sink, if desired in certain embodiments; the rectangular configuration lends itself to convenient, inexpensive sheet metal construction suitable for large scale mass production techniques. The fuel nozzle, ignition device and damper controls are located at the base of the shorter leg of the J-shaped burner unit where they can be readily accessible for convenient adjustment to optimum settings during actual operation. The rectangular burner configuration is versatile for use in many different applications, environments and utilization systems as described, including applications similar to those which have heretofore been limited to gas burners and for modular arrangements of multiple burners stacked side-by-side for great heat release in a relatively compact volume. Multifuel burning capability is provided for interchangeably using fuel oil, kerosene or gasoline while achieving substantially the same desirable blue-flame characteristics in each case, suitable for mobile home applications, emergency heating, garages, use in remote locations, etc. A relatively cool fluepipe is achieved such that the conventional expensive brick or tile chimney can be eliminated.

Description

United States Patent Bailey [15] 3,652,194 1451 Mar. 28, 1972 [54] BLUE-FLAME LIQUID-FUEL BURNER PROCESS, APPARATUS AND UTILIZATION SYSTEMS Frank W. Bailey, 663 Black Oak Ridge Road, Wayne, NJ. 07407 [22] Filed: Sept. 24, 1969 [2l] Appl.No.: 860,662

[72] Inventor:

521 u.s.c1 ..431/9,110/49,122/230, 431/116 51 Int.Cl ..F23m9/06 5s FieldofSearch ..43l/9,1l5,ll6;1l0/49; 122/230 56 References Cited U ITED STATES PATENTS 7 2,688,360 9/1954 Haynes et al.' ..431 115 3,078,914- 2/1963 Bigelow ..431/115 FOREIGN PATENTS 0R APPLICATIONS 565,345 3/1958 Belgium ..43 Ill l5 Primary Examiner-Edward G. Favors. Attorney Bryan, Parmelee, Johnson & Bollinger [57] ABSTRACT Blue-flame burner process, apparatus and utilization systems producing a quiet,.stable, essentially sootless blue flame from liquid fuel, particularly hydrocarbon fuels, fuel oil and the like and producing substantially complete combustion of the fuel, being more efficient than conventional oil burners and eliminating particulate matter in the exhaust products, contributing to substantially reduced air pollution and additionally providing more efficient utilization of the heat generated. In the blue-flame process the kinetics of combustion are controlled by close and effective coupling to a .heat sink, and novel close coupling systems with higher performance heat exchangers are provided. Compact, lightweight inexpensive burner units are provided which are adapted to be constructed with a generally rectangular J-shaped configura-' tion adapted for close coupling to a planar area of a heat sink,

if desired in certain embodiments; the rectangular configuration lends itself to convenient, inexpensive sheet metal construction suitable for large scale mass production techniques. The fuel nozzle, ignition device and damper controls are located at the base of the shorter leg of the J-shaped burner unit where they can be readily accessible for convenient ad- 7 justment to optimum settings during actual operation. The

rectangular burner configuration is versatile for use in many difierent applications, environments and utilization systems as described, including applications similar to those which have heretofore been limited to gas burners and for modular arrangements of multiple burners stacked side-by-side for great heat release in a relatively compact volumev Multifuel burning capability is provided for interchangeably using fuel oil, kerosene or gasoline, while achieving substantially the same desirable blue-flame characteristics in each case, suitable for mobile home applications, emergency heating, garages, use in remote locations, etc. A relatively cool fluepipe is achieved such that the conventional expensive brick or tile chimney can be eliminated.

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PATENTEDMAR28 1972 SHEET 8 BF 8 Y E m L RI E Z 5 3 TB R N. 0 W n K WN A A m BLUE-F LAME LIQUID-FUEL BURNER PROCESS, APPARATUS AND UTILIZATION SYSTEMS DESCRIPTION The present invention relates to blue-flame liquid-fuel burner process, apparatus, and utilization systems for producing a stable blue flame from liquid fuel, particularly hydrocarbon fuels, more particularly fuel oil and the like. The resulting blue flame is quiet and provides less excess air with complete, soot-free combustion, thus, being more efficient than conventional yellow flame burners and eliminating particulate matter in the exhaust products. The invention provides means to advantageously control the flame temperature by controlling the amount of recirculated gases and their degree of cooling as they travel the recirculation path. The invention thus provides substantially reduced air pollution, by eliminating particulate matter and minimizing oxides of nitrogen in the emission products and a number of important operating advantages are provided in a wide variety of utilization systems, as will be explained further below.

Conventional burners which have been in use prior to the present invention for burning liquid hydrocarbon fuels, fuel oil and the like produce yellow or yellowish-orange flames which are noisy, are characterized by incompletecombustion, and often deposit soot in the associated heat exchanger surfaces, in theflue or chimney or discharge particulate matter into the atmosphere. Such yellow or yellow-orange flames have the characteristic that any cool areas within the firebox tend to quench and arrest the combustion in the localized regions of the cool areas, causing carbon precipitation and build-up of unburned carbon on them. The carbondeposits area fire hazard, impede heat transfer and reduce heat transfer efficiency. Such conventional combustion systems are therefore not compatible with close coupled heat exchange devices. Prior fuel oil burners, in practice, involve a compromise between minimum excess air and smoke or soot conditions. Alteration in prior burner back pressure due to flue or heat exchanger blockage rapidly reduces excess air and aggravates the smoke or soot conditions.

Among the advantages of the blue-flame liquid-fuel burner process, apparatus and utilization systems of the present invention are those resulting from the fact that they enable liquid hydrocarbon fuel, such as fuel oil and the like, to be burned with a quiet, stable, efficient blue flame in which substantially complete combustion occurs with little excess air. The firebox and heat exchange surfaces remain cleaner than with conventional yellow flame burners, improved heat transfer is enabled to occur due to the use of cooler and highly connective heat exchange surfaces, and reduced maintenance and down time are achieved. The blue flame produced by utilizing this invention to burn fuel oil has the capability of a substantial dwell time in and about the firebox and heat exchange surfaces while substantially complete combustion occurs and therefore can conveniently be utilized with cooperative advantage in a wide variety of efficient and effective utilization systems which are more compact and less expensive than conventional fuel oil heating systems previously in use.

A summary of the features, aspects and advantages of the blue-flame liquid-fuel burner process, apparatus and utilization systems of the present invention includes the following:

1. in the blue flame process as provided by the invention, the flame has its temperature controlled by the amount of recirculated gases and by the degree of cooling of these gases provided by close coupling with a heat sink. The combustion box 40 provides the optimum temperature and residence time to complete all chemical reactions and to allow the products therefrom to impinge on the heat sink. The kinetics of combustion are controlled by mixing of diluent gases at a temperature optimized by coupling to a heat sink.

2. The suction eductor system enables complete utilization of the combustion volume 40. The combustion process stabilizes due to recirculation of combustible efflux from the mixing tube to a plane slightly downstream from the tertiary air ports. These factors all cooperate to provide complete combustion and to efficiently utilize the close coupled, high pressure drop, cool heat exchanger surfaces downstream from the combustion chamber.

3. A compact, light-weight bumerunit is provided, which is adapted to be constructed with a generally rectangular configuration enabling close coupling to a planar area of a heat sink.

4. The compact burner unit as disclosed has a J-shape with the fuel nozzle, ignition device and damper controls located at the base of the shorter leg of the J-shape where they can be readily accessible for adjustment to optimum settings during actual operation. l

5. The rectangular, J-shape burner lends itself to convenient, inexpensive sheet metal construction, suitable for large-scale mass production techniques.

6. The process and apparatus are extremely versatile for use in many different applications, and environments and utilization systems, including many of those which have heretofore been limited to gas burners.

7. A clean blue flame is produced substantially sootless, contributing to substantially reduced air pollution.

8. The noise level of the blue flame is lower than that for yellow flame combustion. i

9. The process and blue-flame burner apparatus are reliable in operation.

10. The J-shaped burner unit is easy to service. It is so compact and light-weight that it can quickly and conveniently be removed and replacedby another burner unit so that the original canbe returned to the maintenance plant, thus providing centralized servicing using interchangeable, com,- pact mass-produced burner units.

11. The apparatus and fuel utilization systems shown are simple, reliable and low in cost. I

12. A multi-fuel burning capability is provided by the 'process and apparatus. Fuel oil, kerosene or gasoline may be used while providing substantially the same blue-flame characteristics, thereby being convenient for mobile home applications, garages, remote locations where fuel availability is limited, for emergency heating, etc. It is noted that the air atomizing nozzle 30 may also function as a gaseous fuel injector without alteration of other components so that the combustion systems as shown also have gas connection capability.

13. The rectangular'burner configuration which can be obtained lends itself to modular arrangements of multiple burners for greatly increasing the over all heat release capacity in a relatively compact system.

14. Additional advantages in connection with the forced removal of relatively cool exhaust products are (a) reduced ignition pressure pulsations due to constant'induced pressure differential, i.e., the burner starts without a loud pressure pulse or hang because there is no substantial pressure build up during transient starting conditions; (b) simplified compact structures are achieved; and (c) a large pressure difierential is provided across the heat exchanger.

15. The many novel aspects of the invention enable fuel oil and other liquid fuels to be utilized more efficiently and more conveniently.

The various aspects, objects and advantages of the present invention will in part be pointed out and will in part become apparent from the following description when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view, with portions cut away to reveal the interior, of a blue-flame liquid-fuel burning heater system embodying the present invention for heating hot water FIG 3 is a front elevational view, as seen in the direction 3- 3 in FIG. 2, with the burner apparatus removed to disclose the pair of openings into which it fits. Also, in FIG. 3 the top portion of the housingis shown cut away to reveal the circular end of the cylindrical center-flue tank which contains the water or other liquid to be heated.

FIG. 4 is a perspective view, with portions cut away to reveal the interior, of another blue-flame liquid-fuel burning heater system embodying the process of the present invention, the boiler being very compact and having a single flowthrough conduit for heating water or other suitable liquid such as discussed above for similar purposes as above.

FIG. 5 is a longitudinal and elevational sectional view of the heater system of FIG. 4.

FIG. 6 is a front sectional view, taken along the two portions of the line 6-6 in FIG. 5.

FIG. 7 is a sectional view of a blue-flame liquid-fuel burner having a generally J-shaped configuration, including two leg portions and an interconnecting back portion.

FIG. 8 is an end elevational view as seen looking in the direction 8-8 in FIG. 7. T

FIG. 9 is an elevational view of the other end of the blueflame burner of FIG. 7 as seen looking in the direction 9-9.

. FIG. 10 is a perspective view of a modular boiler system in which multiple blue-flame liquid-fuel burner units having generally rectangular configuration are stacked together in generally spaced, parallel side-by-side arrangement, each associated with a small rectangularboiler, thus providing large heat release capacity in a relatively compact volume;

FIG. 11 is a front elevational view of the modular boiler system of FIG. 10; I

FIG. 12 is a perspective view of another modular boiler system similar to FIG. 10; and I FIG. "13 is a perspective view of a hot air heating furnace embodying the invention. Referring to FIGS. 1, 2 and 3 of the drawings in greater detail, there is shown a blue-flame liquid-fuel burner heater system for heating hot water or other suitable liquid, as mentioned above. For convenience of reference the system 20 may be referred to as a hot water heating system, but the reader is asked to note that this system can be used to heat other suitable liquids without departing from the scope of the invention as claimed.

This heating system 20 produces a quiet, stable, efficient, blue flame when burning liquid hydrocarbon fuels and is well suited for burning fuel oil, kerosene or gasoline, interchangeably. In the following description the particular fuel being burned is No. 2 fuel oil.

In this heating system 20 there is employed a vigorous forced venting action for removing the exhaust products. This forced venting is produced by an eductor, as will be described further below. The relatively cool exhaust gases can be removed through an uninsulated flue. Other advantages of this forced venting are summarized above and will be referred to further below. p v

The heating system 20 includes a blue-flame burner 22 having a generally J-shaped configuration including a first hollow leg section'24 which serves as a mixing and preparation zone;

a second hollow leg section 26 which serves as a recirculation path, and an interconnecting hollow section 28 which joins the ends of the two

leg sections

24 and 26. The J-shaped configuration provides various structural and dynamic advantages. It allows structural support for the relatively short mixing tube 24, and it allows a hydrostatic balance in the two

leg sections

24 and 26 when adapted with a relatively high pressure drop heat exchanger having a vigorous eductor for the exhaust products. The pressure drop in the extended leg section 26 is relatively small and therefore avoids short circuiting of the combustion gases, i.e., avoids any reverse flow tendency through the mixing tube. Thus, the jet action of an air atomizing nozzle 30 is then capable of maintaining the proper flux of recirculating gases from the optimum point 106 in relation to the heat exchanger.

Liquid fuel is fed through a fuel line 29 and is atomized by the nozzle 30, the atomized fuel being sprayed into the interior 32 of the first hollow leg section 24. The particular fuel nozzle 30 shown is of the air atomization type, with air under pressure being supplied through an air line 34.

The region 32 within the hollow leg 24 serves as a fuel mixture preparation zone, as will be explained in detail further below, and the end 36 of this hollow leg provides a discharge muzzle from which issues a stable, quiet, efficient flue flame 38. The flame is directed into an elongated firebox 40 extending horizontally and having a rectangular parallelepiped configuration.

The bottom wall 42, side walls 44 and end wall 46 of the firebox 40 are constructed of sheet metal, each of these sur-' faces being line by a rectangular panel of stiff insulation board 48, such as glass fiber mats, thus providing for inexpensive mass production. The upper surface of the firebox 40 is also lined by insulation 48 and includes'a relatively heavy metal plate 50 which serves as a heat sink in close and effective heat exchange coupling with the hollow burner leg 26. In this embodiment the burner leg 26 rests directly upon the heat sink plate 50 in intimate face-to-face contact providing a large area 75 of heat-conduction relationship therewith. I

Extending up from both longitudinal edges of the heat sink plate 50 area pair of housing side walls52 and 54 (FIG. 3) which effectively provide a cradle at 55 for receiving a cylindrical center-flue heat exchange tank '56. This tank'56 is of a stock type such :as used in gas-fired hot water heaters, except that in the System20 the tank 56 is oriented horizontally in the cradle 55 with its concave end 57 at the left in FIG. 2 and its convex end 58 at the right.

In' this advantageous system 20, the hemicylindrical tank surface 59 (FIG. 3) extending downwardly between the

housing walls

52 and 54 plus the concave end 57 plus the horizontal central flue 60, all serve as heat exchange surfaces for heating the liquid 62 within the tank 56. Therefore, as much heat as possible is extracted from the hot gases 64 which flow from the firebox 40 upwardly through a port 66 into a first heat exchange chamber 68 below the tank surface 59.

Between the concave tank end 57 and an end housing wall 70 and between portions of the

side housing walls

52 and 54 is defined a second heat exchange chamber 72 (FIG. 2) which communicates with the first chamber 68. A' third heat exchange chamber 74 is provided by the central tank passage 60.

The interior surfaces of the first heat exchange chamber 68 are lined by insulation material 48, except for the contact area 75 adjacent the burner leg 26 and except for the tank surface 59. The interior of the housing wall 70 is insulated by material 48 as is also the interior of the hood 76 which connects the wall 70 with the lip 78 of the concave tank end 57.

A vigorous forced venting of the exhaust products is employed, as discussed above, which maintains all of the

heat exchange chambers

68, 72, 74 and the firebox 40 at sub-atmospheric pressure. The outlet end of the tank passage 60 is connected to a suction plenum chamber 80 having a Vent uri throat 82 connected to an exhaust duct 84. A blower 86 has its nozzle 88 directed up through the Venturi 82 for drawing the exhaust gases 90 up the duct 84. Alternativeforced venting means can be employed, such as a blower wheel or fan in the flue 84, in lieu of the

eductor

86, 88.

The liquid 62 to be heated is supplied through a pipe 92 extending down near the cylindrical wall 59, and the hot liquid is withdrawn through a pipe 94.

The heavy heat sink plate 50 is supported at its four corners by legs 96 (FIG. 1 and a pair of cross braces 98 extend across beneath the firebox 40.

The sub-atmospheric pressure in the firebox 40 causes secondary air to be pulled in through a plurality of air intake apertures 100 surrounding the nozzle 30. These apertures or ports 100 can be adjusted ineffective area by means of an adjustable rotatable damper disk having matching openings. This damper disk can be adjusted and locked in place by a set screw, as will be understood. A spark plug 102 energized by an insulated ignition wire 104 serves to ignite the fuel.

Tertiary air may be drawn directly into the combustion volume 40 through a plurality of apertures 103 (FIG. 3) which are located near the burner leg 24. These apertures or ports 103 can be adjusted in effective area by means of slidable dampers having matching openings which are locked in their adjusted positions by means of set screws.

In operation a minor proportion of the partially cooled hot gases 64 are drawn into the intake end 106 of the hollow burner leg 26. These recirculated gases 108 (FIG. 2) are further cooled by substantial heat exchange in the elongated recirculation conduit provided by the interior of the hollow burner leg 26. The withdrawn heat passes through the large area of contact 75 into the heat sink plate 50, and the cooled gases 108 pass through the interconnection passage 28 to enter the mixture preparation zone 32.

In the zone 32 the cooled recirculated gases dilute the fuelair mixture and allow the maintenance of a stable, blue-flame combustion process, thus providing a stable, quiet, efficient, soot-free blue flame 38. It isnoted that there is a long effective residence time of the hot gases in the four

interconnected chambers

40, 68, 72, and 74 so that highly effective and efficient heat exchange occurs. I

The fuel nozzle 30, dampered air apertures 100 and ignition device 102 are all conveniently accessible for adjustment during actual operation of the system 20. Moreover, the'J-shaped burner 22 can conveniently and simply be withdrawn from the two

openings

110 and 112, which accommodate the

burner legs

24 and 26, respectively, for removal and replacement servicing.

The heating system 120 shown in FIGS. 4, 5, and 6 is generally similar to the system described above, and corresponding reference numbers are used for the elements performing corresponding functions. The important differences between the blue-flame heating system 120 and the system 20 will be described. In lieu of the tank '56 and associated chambers and elements, there is a compact single flow-through conduit 122 having a plurality of radial longitudinal heat exchange fins 124 secured to it. The cold liquid inlet line 92 connects to one end of the flow-through conduit 122 and the hot liquid outlet line 94 connects to the other end. It is noted that the liquid 62 (FIG. 5) passes through the conduit 122 in a direction counter to -the flow of the hot gases 64 in advantageous counter-current heat exchange relationship. An insulation blanket 126 fills up the space within the top sheet metal housing 128 above the fins 124, thus forcing all of the hot gases 64 to pass among these fins.

A small quartz glass observation window 130 (FIG. 5) may be located in a view port 132 at the back end of the firebox 40 for observing the blue flame 38.

The burner apparatus 22 is shown in greater detail in FIGS. 7, 8 and 9. It includes a conical baffle 140 which serves as a flame holder and induces a thorough interrnixing of the cooled recirculated gases 108 with the incoming fuel mixture 141 in the region 32. The adjustable damper disk 142 and set screw 144 are shown. A mounting bracket 146 is shown, which may be attached to an external mounting bracket outside of the firebox 40. The spark plug 102 is preferably located above the level of the air atomizing nozzle to avoid oil accumulation on the ceramic insulator of the electrode in the spark plug.

An important advantage of the generally square burner leg section 24 is that it provides four internal recirculation quadrants 137 into which eddying vortices 139 are established for stabilizing the ignition process and for improving the thorough mixing of the recirculated gases 108 and the fresh incoming fuel-air mixture from the nozzle 30 and the air ports 100.

The modular heating system 160 shown in FIGS. 10 and 11 includes a multiplicity of the J-shaped burners 22 mounted in spaced, parallel, side-by-side relationship. The hollow recirculation leg 26 of each burner 22 is secured to the lower surface of a small rectangular boiler tank 162. Thus, the individual tanks 162 serve as heat sinks for cooling the recirculated gases. The hot gases 64 pass upwardly between the parallel side surfaces of the multiple modular boilers 162 in good heat exchange relationship therewith. The spark plugs 102 are shown in an alternate location below the level of the nozzles 30 to indicate the versatility of the burner. The preferred position is shown in FIGS. 1, 2, 5 and 7. In practice the nozzle 30 and the spark plug 30 are mounted on a common mounting plate which is detachably secured to the burner head for mounting in either position as may be desired.

In this modular system 160 which has a common firebox 40 for all of the burners 22, a single spark plug ignitor may be employed, if desired, rather than having an ignitor for each burner.

In FIG. l2 is shown a modular heating system similar to that shown in FIG. 10 and. 11. The individual tanks 162 are interconnected by a water inlet line 164 and a water outlet line In FIG. 13 is shown a hot air heating fumace 170. In the top portion of the furnace shell 172 is a heat exchanger 174 for heating hot air. A circulating air fan 176 of the centrifugal blower type directs air to the lower surface of the base of the firebox 40. An extended length of rectangular pipe 26 is located in contact with the bottom of the firebox and is located beneath a horizontal bafi'le 180 for directing the com-. bustion products in heat exchange relationship with the base of the firebox. A large rectangular outlet 182 is provided for discharging the heated air from the heat exchanger 174.

The modular systems of FIGS. 10-13 are well adapted for high intensity radiant energy heat transfer from the walls defining the common combustion volume 40 to the surfaces of the

heat exchangers

162 or 174.

In the embodiment of FIGS. 10-13, the exhaust products may be removed by thermogravity flow at moderate firing rates; whereas a forced pressure differential is used for higher firing rates.

What is claimed is:

l. A process for producing blue-flame combustion of liquid, hydrocarbon fuel comprising the steps of introducing a combustible mixture of atomized liquid fuel and air into a mixing and preparation zone, igniting said combustible mixture and burning the fuel in a combustion volume, recirculating combustion products from a region in the combustion volume where the chemical reactions are substantially complete, cooling the recirculated products by passing the recirculating products in heat transfer relationship with a heat sink, returning a portion of the cooled recirculated gases to the combustion volume, thoroughly inter-mixing the returned portion of the cooled recirculated gases with the fresh fuel air combustible mixture by commonly passing them through said mixing zone, said mixing zone having a polygonal cross-sectional configuration, preferably square, providing for internal recirculation quadrants, forming multiple internal recirculation paths in said mixing zone quadrants by establishing eddying vortices therein, thereby diluting and cooling the mixture flowing through said mixing zone sufficiently to prevent the establishment of a flame front within said mixing zone, said mixing zone being substantially shorter in length than the recirculation path, and discharging the cooled diluted ignited mixture from the mixing zone thereby providing a stabilized combustible mixture discharging from said mixing zone in blue-flame combustion in the combustion volume.

2. A system for heating a fluid by blue-flame combustion of liquid hydrocarbon fuel comprising a heat exchanger, means for introducing the fluid into the heat exchanger and for removing the heated fluid therefrom, means defining a combustion volume, conducting means defining a region for conducting combustion products from said combustion volume into heat exchange relationship with said heat exchanger, at least one burner unit having a generally J-shaped configuration including a first substantially open hollow leg section directed into said combustion volume, injecting means for injecting atomized liquid fuel and air mixture into said first leg section, ignitor means for igniting the fuel-air mixture, a

' fuel-air mixture, a second hollow leg section for receiving a second hollow leg section for receiving a portion of the com 1 and a hollow interconnection section interconnecting one end of each of said legs for returning the partially cooled combustion products from said second leg to said first leg to be mixed with the fuel and air mixture, thereby controlling the combustion kinetics in said combustion volume to produce blue-flame combustion in said volume.

3. A system as claimed in claim 2 in which a plurality of said burner units are positioned in spaced side-by-side relationship with their respective legs parallel with each other.

4. Apparatus forproducing blue-flame combustion with liquid fuelscomprising a burner unit having a generally J- shaped configuration including a first hollow leg section of generally square cross section serving as a mixing and preparatory zone, a second hollow leg section sewing as a recirculation path for combustion products, said first hollow leg section being substantially shorter than said second hollow leg section, an interconnecting hollow section joining the ends of the two leg sections, and a vortex generating bafi'le means positioned in the first hollow leg section near the juncture with said interconnecting hollow section. 5. Apparatus as claimed in claim 4 in which said vortex generating baffle means are provided by a downstream conveyent baffle. 6. Apparatus as claimed in claim 5 in which said downstream conveyent baffle has a conical configuration.

7. Apparatus for producing blue-flame combustion with liquid fuels comprising a burner unit having a generally J- shaped configuration including a first hollow leg section serving as a mixing and preparatory zone, a second hollow leg section serving as a recirculation path for combustion products, an interconnecting hollow section joining the endsof the two leg sections, and an air atomizing nozzle associated with said interconnecting hollow section, said nozzle being directed transversely of said interconnecting section into said first hollow leg section, said interconnecting hollow section and an inlet means near said nozzle.

8. A system for heating a fluid by blue-flame combustion of liquid hydrocarbon fuel comprising at least one of heat exchanger means for introducing the fluid into the heat exchanger and for removing the heated fluid therefrom,

means defining a combustion volume, conducting means defining a region for conducting combustion products from said combustion volume into heat exchange relationship with said heat exchanger, at least one burner unit having a generally J-shaped configuration including a first substantially open hollow leg section directed into said combustion volume,

I injecting means for injecting atomized liquid fuel and air mixtures into said first leg section, ignitor means for igniting the portion of the combustion products after they have passed in heat exchange relationship with said heat exchanger, said second leg section being contained substantially within the conducting region and in close and effective heat exchange contact with a heat sink, and a hollow interconnection section interconnecting one end of each of said legs for returning the partially cooledcombustion products to said first leg to be- 10. A modular system for heating a fluid by blue-flame com- I bustion of liquid hydrocarbon fuel comprising a plurality of heat exchangers including means for passing fluid therethrough, a combustion chamber, said combustion chamber including at least one ignitor means for igniting a fuel-air mixture, conducting means defining a region for conducting combustion products from said combustion chamber into heat exchange relationship with said heat exchanges, a plurality of J-shaped burner units mounted in spaced, parallel, side-by-side relationship in said chamber, said burner units having a first substantially open hollow leg section directed into said combustion chamber, injecting means for injecting atomized liquid fuel and air mixture into said first leg section; a second hollow leg section for receiving a portion of the combustion products after they have passed in heat exchange relationship with saidheat exchangers, said second leg section being contained substantially within the conducting region and in close and effective heat exchange contact with a surface of one of said heat exchangers, and a hollow interconnection section interconnecting one end of each of said legs for' returning the partially cooled combustion products to said 1 first leg to be mixed with the fueland air mixture, thereby controlling the combustion kinetics in said combustion volume to produce blue-flame combustion in said volume and providing high intensity radiant energy heat transfer from the combustion chamber to the heat exchange surface.

11. Apparatus for producing blue-flame combustion with liquid fuels comprising a burner unit having a generally J- shaped configuration including a first substantially open shorter hollow leg section of generally square cross section

Claims

2. A system for heating a fluid by blue-flame combustion of liquid hydrocarbon fuel comprising a heat exchanger, means for introducing the fluid into the heat exchanger and for removing the heated fluid therefrom, means defining a combustion volume, conducting means defining a region for conducting combustion products from said combustion volume into heat exchange relationship with said heat exchanger, at least one burner unit having a generally J-shaped configuration including a first substantially open hollow leg section directed into said combustion volume, injecting means for injecting atomized liquid fuel and air mixture into said first leg section, ignitor means for igniting the fuel-air mixture, a second hollow leg section for receiving a portion of the combustion products after they have passed in heat exchange relationship with said heat exchanger, said second leg section being contained substantially within the conducting region and a hollow interconnection section interconnecting one end of each of said legs for returning the partially cooled combustion products from said second leg to said first leg to be mixed with the fuel and air mixture, thereby controlling the combustion kinetics in said combustion volume to produce blue-flame combustion in said volume.
3. A system as claimed in claim 2 in Which a plurality of said burner units are positioned in spaced side-by-side relationship with their respective legs parallel with each other.
4. Apparatus for producing blue-flame combustion with liquid fuels comprising a burner unit having a generally J-shaped configuration including a first hollow leg section of generally square cross section serving as a mixing and preparatory zone, a second hollow leg section serving as a recirculation path for combustion products, said first hollow leg section being substantially shorter than said second hollow leg section, an interconnecting hollow section joining the ends of the two leg sections, and a vortex generating baffle means positioned in the first hollow leg section near the juncture with said interconnecting hollow section.
5. Apparatus as claimed in claim 4 in which said vortex generating baffle means are provided by a downstream conveyent baffle.
6. Apparatus as claimed in claim 5 in which said downstream conveyent baffle has a conical configuration.
7. Apparatus for producing blue-flame combustion with liquid fuels comprising a burner unit having a generally J-shaped configuration including a first hollow leg section serving as a mixing and preparatory zone, a second hollow leg section serving as a recirculation path for combustion products, an interconnecting hollow section joining the ends of the two leg sections, and an air atomizing nozzle associated with said interconnecting hollow section, said nozzle being directed transversely of said interconnecting section into said first hollow leg section, said interconnecting hollow section and an inlet means near said nozzle.
8. A system for heating a fluid by blue-flame combustion of liquid hydrocarbon fuel comprising at least one of heat exchanger means for introducing the fluid into the heat exchanger and for removing the heated fluid therefrom, means defining a combustion volume, conducting means defining a region for conducting combustion products from said combustion volume into heat exchange relationship with said heat exchanger, at least one burner unit having a generally J-shaped configuration including a first substantially open hollow leg section directed into said combustion volume, injecting means for injecting atomized liquid fuel and air mixtures into said first leg section, ignitor means for igniting the fuel-air mixture, a second hollow leg section for receiving a portion of the combustion products after they have passed in heat exchange relationship with said heat exchanger, said second leg section being contained substantially within the conducting region and in close and effective heat exchange contact with a heat sink, and a hollow interconnection section interconnecting one end of each of said legs for returning the partially cooled combustion products to said first leg to be mixed with the fuel and air mixture, thereby controlling the combustion kinetics in said combustion volume to produce blue-flame combustion in said volume.
9. A system as claimed in claim 3 in which a plurality of said burners are positioned in spaced side-by-side relationship with their respective legs parallel with each other in conjunction with a plurality of heat exchangers.
10. A modular system for heating a fluid by blue-flame combustion of liquid hydrocarbon fuel comprising a plurality of heat exchangers including means for passing fluid therethrough, a combustion chamber, said combustion chamber including at least one ignitor means for igniting a fuel-air mixture, conducting means defining a region for conducting combustion products from said combustion chamber into heat exchange relationship with said heat exchanges, a plurality of J-shaped burner units mounted in spaced, parallel, side-by-side relationship in said chamber, said burner units having a first substantially open hollow leg section directed into said combustion chamber, injecting means for injecting atomized liquid fuel and air mixture into said first leg section; a second hollow lEg section for receiving a portion of the combustion products after they have passed in heat exchange relationship with said heat exchangers, said second leg section being contained substantially within the conducting region and in close and effective heat exchange contact with a surface of one of said heat exchangers, and a hollow interconnection section interconnecting one end of each of said legs for returning the partially cooled combustion products to said first leg to be mixed with the fuel and air mixture, thereby controlling the combustion kinetics in said combustion volume to produce blue-flame combustion in said volume and providing high intensity radiant energy heat transfer from the combustion chamber to the heat exchange surface.
11. Apparatus for producing blue-flame combustion with liquid fuels comprising a burner unit having a generally J-shaped configuration including a first substantially open shorter hollow leg section of generally square cross section serving as a mixing and preparatory zone, a second open unobstructed longer hollow leg section of generally rectangular cross section serving as a recirculation path for combustion products, and an interconnecting hollow section joining the ends of the two leg sections.
12. Apparatus as claimed in claim 11 in which the length of the first hollow leg section is less than three and more than one times its width.