Title of Invention

"A DUAL FUEL BURNER FOR PRODUCING A RELATIVELY SHORT TURBULENT FLAME OF INTENSE HEAT"

Abstract

The invention provides a dual fuel burner which is capable of producing a short turbulent flame of intense heat and suitable for burning at a fast rate fuel gases of all calorific values, especially of low calorific value, such as blast furnace gases, supplied at a low pressure of 50-150 mmWC and liquid fuels of all types, singly or simultaneously, and for applications in sinter ignition hoods and boilers. The burner comprises : (A) a gas burner having a gas pipe containing a cylindrical part into which fuel gases are fed through a gas inlet pipe and a tapered part acting as a gas nozzle through which fuel gases are injected into a mixing chamber, and an air chamber with an air nozzle and an air Inlet pipe for supplying air circulating round the gas nozzle and discharging through the air nozzle into the mixing chamber and a refractory quirl fitted on the outlet end of the air nozzle; and (B) a liquid fuel gun having an innermost pipe, acting as an emulsion tube, and being disposed concentrically inside a dummy pipe which in turn being disposed concentrically inside a gas pipdjprovided with an atomising nozzle for producing an emulsion of liquid fuels and air/steam therein, the liquid fuel gun being connected at input end and at an emulsion nozzle at the output and for discharging the emulsion of liquid fuels and air/ steam into the mixing chamber, connected at outlet end of the innermost pipe.

Full Text

The present invention relates to a dual fuel burner capable of producing a short turbulent flame of intense heat; The invention relates more particularly to a dual fuel burner which is suitable for burning at a fast rate fuel gases of all calorific values, especially oJ relatively low calorific value r(i.e. blast furnace gas), 20-40% carbonra on oxide content and low pressure, and liquid fuels of all types such as low sulphur high stock (LSHS) oils and light diesel oils (LDO), supplied singly or simultaneously, and is suitable for , applications in sinter ignition hoods and boilers requiring burners of short and intense flame. In the Indian Patent Application.No.2233/Del/95 a burner which is operable from dual fuels such as lean gases and high-viscous oils, supplied simultaneously or singly, hes been disclosed. This burner is suitable for generating a high-thrust flame of stable and adjustable shape required for applications in heat-treatment and reheating furnaces and comprises at least five concentric tubes. Pre-heated high-viscous oils are fed at the input end of the innermost tube and discharged through an oil nozzle fitted at the outlet end of the tube into an emulsion chamber into which an atomising medium such as compressed air or steam is supplied through the annular space between the innermost tube and the first outer tube adjacent thereof through a multi-hole nozzle to produce an emulsion of oil and air or of oil' and steam in the emulsion chamber. The second outer tube adjacent the first outer tube is a dummy tube which is meant for holding an air swirler at its outlet end and increasing the diameters of the remaining outer tubes. Air for combustion of gases/oils is supplied, through the annular space between the second outer tube and third outer tube adjacent the second outer tube, and the air swirler, into a mixing chamber in which the said emulsion and air are mixed thoroughly. Fuel gases are supplied into the mixing chamber, through the annular space between the third outer tube and fourth outer tube adjacent the third outer tube, and a multi-hole gas nozzle fitted at the outlet end of the fourth outer tube. In the Indian Patent Application No.2234/Del/95, a burner of modified design and construction, operable efficiently from lean gases and low viscous oils supplied simultaneously or singly, has been disclosed. The burner comprises at least three concentric tubes of which the Innermost one is meant for feeding low viscous oils into an oil nozzle detachably fitted to the outlet-end thereof. Through the annular space between the innermost tube and the adjoining first outer tube, compressed air is blown into an air nozzle, detachably fitted to the outlet end of the oil nozzle. Low viscous oils and compressed air get thoroughly mixed in the air nozzle to produce an emulsion of oils and air, which Is discharged into a gas nozzle detachably fitted to the outlet end of the air nozzle, where it is thoroughly mixed with the lean gases supplied therein through'the annular space between the first outer tube and the second outer tube adjacent the first outer tube. The mix of low viscous oils, compressed al¬and lean gas is burnt to produce a stable and firmly anchored flame in a refractory quarl fitted at the outlet end of the gas nozzle. One drawback of the existing dual fuel burners is that the burning rate of fuel gases and oils is not sufficiently fast i.e. not exceeding 50 kg/hr for oils and 800 NM3/hr for gases for producing a short turbulent flarae of intense heat. Another drawback of the existing dual fuel burners is that the gases are required to be supplied at a relatively high pressure of 100-600 mraWC. The object of the present invention is to provide a dual fuel burner which is capable of producing a short turbulent flame of intense heat by burning fuel oils and gases at a faster rate of upto 2000 kg/hr for oils and 2000 NM-yhr for gases supplied at a lower pressure of 50-150 mraWC. The invented burner comprises basically two separate assemblies, namely, one assembly for burning fuel gases, called •gas burner1 and other assembly, for burning liquid fuels, called 'liquid fuel gun1. The gas burner comprises a gas pipe and an air chamber. The gas pipe has a cylindrical part, into which the fuel gases are fed through a gas inlet pipe, and a part tapering towards the outlet end of the gas pipe, acting as a gas nozzle, through which fuel gases discharge into a mixing chamber. The air chamber has also a substantially cylindrical part into which air for combustion of the fuel gases/liquid fuels is supplied through an air inlet pipe, which is connected tangentially to the cylindrical air chamber and a part tapering towards the mixing chamber, acting as an air nozzle, through which air foi combustion of the fuel gases/liquid fuels discharges into the mixing chamber. The air chamber and air nozzle are so designed and constructed that these surround the gas nozzle and make the air supplied circulate round the outside surface of the gas nozzle before it is discharged into the mixing chamber through the air nozzle, producing thereby an Intimate mix of the air and fuel gases/liquid fuels, which can be burnt at a relatively fast rate e.g. upto 2000 kg/hour for liquid fuels and 2000 NM3/hours for fuel gases ; generat'ifuja zone of negative pressure adjoining the exit end of the gas nozzle in the mixing chamber and thus permit tih«f supply of fuel gases at a relatively low pressure of 50-150 mmWC. The liquid fuel gun is disposed concentrically inside the gas burner and comprises an Innermost pipe, called emulsion tube, which may be straight or bent, and a concentric outer pipe of larger diameter, called dummy pipe. An atomising nozzle is connected to the input end of the emulsion tube, into which compressed air/steam and liquid fuels are supplied for producing an emulsion of liquid fuels and air/steam. At the outlet end of the emulsion tube an emulsion nozzle is fitted, through which the emulsion of liquid fuels and air/steam supplied at the input end of the emulsion tube discharges into the said mixing chamber of the gas burner. The invention is now described fully and particularly in an unrestricted manner with reference to the accompanying drawings, in which Figure 1 is sectional elevation of the invented burner; and Figure 2 is a sectional elevation of the atomising nozzle on an enlarged scale. Referring to Figure 1, the gas burner comprises gas pipe 6 and air chamber 4. The gas pipe 6 has a cylindrical part 9 into which fuel gases are fed through gas inlet pine 5 and a tapered part 2 acting as a gas nozzle through which the fuel gases discharge into' mixing chamber 16. The air chamber A is substantially cylindrical and is provided with an air nozzle 1 which is tapered towards the mixing chamber. The air for combustion of fuel gases is fed into the air chamber through air inlet pipe 15 which is connected tangentially to the cylindrical air chamber and is allowed to circulate round the gas nozzle 2 before discharging into the mixing chamber through the air nozzle. A refractory quirl 17 is fitted on the outlet end of the air nozzle. The quirl has a straight part 18 and a diverging part 19. The liquid fuel gun comprises an innermost pipe 8, acting as an emulsion tube, disposed concentrically inside a dummy pipe 7 having a flange 9A which is connected to the flange 9B of the cylindrical part 9 of the gas pipe. Pipe 8 has a flange 10 near its input end 11A, which is connected to flange 9A. An atomising nozzle 11B is connected at the input end 11A of pipe 8. The outlet end 8A of pipe 8 is connected to an emulsion nozzle 3 having at least one hole therein, which may be parallel to the axis of the nozzle or divergent therefrom. Referring to Fig. 2, the atomising nozzle 11B comprises a converging part 11C to compress the atomising medium woicn may oe steam or air supplied at a pressure of 2.0 to 10.0 kg/cm2 to the burner through inlet end 12A of pipe 12 into which the atomising nozzle is inserted, and a diverging part 11 for allowing the'atomising medium to expand therein and the emulsion of liquid fuels and air/steam to discharge through the outlet end 12B of pipe 12 into pipe 8 at the input end 11A thereof. On the periphery of the diverging part 11 of the atomising nozzle holes 1A numbering 2 to 12 are prbvided for the entry of liquid fuels into the diverging, part from the chamber 14A formed in the annular space between pipe 12 and diverging part 11 of atomising nozzle. The liquid fuels supplied to the burner through the inlet pipe 13, connected to pipe 12, Is stored in chamber 14A. The invented burner besides being suitable for burning fuel gases supplied at a relatively low pressure of 50-150 mmWC and producing a relatively short flame of intense heat, is capable of achieving complete combustion of fuel gases/liquids at a relatively low excess air coefficient of 1.05 to 2.0, and burning fuel gases and liquid fuels either singly or simultaneously, particularly when the fuel gases are of relatively low calorific value e.g. blast furnace gases. Claim :- 1. A dual fuel burner capable of producing a short turbulent flame of intense heat, the burner being suitable for burning at a fast rate fuel gases of all calorific values, es¬ pecially of low calorific value, such as blast furnace gases, supplied at a low pressure of 50-150 mmWC and liquid fuels of all types, singly or simultaneously, and for applications in sinter ignition hoods and boilers, comprising: (A) a gas burner having gas pipe 6 of cylindrical part 9 into which fuel gases are fed through gas inlet pipe 5 and tapered part 2 acting as a gas nozzle through which fuel gases are injected into mixing chamber 16, and.air chamber 4 with air nozzle 1 and air inlet pipe 15 for supplying air circulating round the gas nozzle and discharging through the air nozzle into the mixing chamber and a refractory quirl 17 fitted on the outlet end of the air nozzle; and (B) a liquid fuel gun having an innermost pipe 8, acting as an emulsion tube, and being disposed concentrically inside a dummy pipe 7 which in turn being disposed concentrically inside gas pipe 6, with atomising nozzle 11B, for producing .an emulsion of liquid fuels and air/steam therein, connected at input end 11A and emulsion nozzle 3, for discharging the emulsion of liquid fuels and air/steam into the mixing chamber, connected at outlet end 8A of pipe 8. 2. The burner as claimed in claim 1, wherein the gas pipe and dummy pipe are connected to each other by means of flanges 9 A and 9B. 3. The burner as claimed, in claims 1 and 2, wherein the dummy pipe and innermost pipe are connected to each other by means of flanges 9A and 10. 4. The burner as claimed in claim 1r wherein the air nozzle is tapered towards the mixing chamber. 5. The burner as claimed in claim 1, wherein the gas nozzle is tapered towards the mixing chamber. 6. The burner as claimed in claim 1, wherein the refractory quirl has a straight part 18 and diverging part 19. 7. The burner as claimed in claim 1, wherein the atomising nozzle has a converging part 11C and a diverging part 11, both said parts being inserted in a pipe 12 having input end 12A into which the atomising medium such as steam and air, is fed, and outlet end 12B, into which the input end 11A of the innermost pipe 8 is fitted, for discharging the emulsion of liquid fuels and air/steam into the innermost pipe 8. 8. The burner as claimed in claim 7, wherein a chamber 14A is formed in the annular space between pipe 12 and diverging part 11 of the atomising nozzle, in which the liquid fuels supplied to the burner through inlet pipe 13 are stored. 9. The burner as claimed in claims 7 and 8, wherein holes 1 numbering 2 to 12 are provided on the periphery of the diverging part 11 of the atomising nozzle for the entry of liquid fuels thereinto from chamber 14A. 10. The burner as claimed in claim 1, vrherein the emulsion nozzle 3 is provided with s.t least one hole whida is parallel to the axis of the nozzle. 11. The burner as claimed in claim 1, wherein the emulsion nozzle 3 is provided with at least one hole which is divergent to the axis of the nozzle.

Documents:

211-del-1997-abstract.pdf

211-del-1997-claims.pdf

211-del-1997-correspondence-others.pdf

211-del-1997-correspondence-po.pdf

211-del-1997-description (complete).pdf

211-del-1997-drawings.pdf

211-del-1997-form-1.pdf

211-del-1997-form-19.pdf

211-del-1997-form-2.pdf

211-del-1997-form-6.pdf

211-del-1997-gpa.pdf