Title of Invention

"A PILOT BURNER IGNITION APPARATUS FOR USE IN COMBUSTION CHAMBERS"

Abstract

1. A pilot burner ignition apparatus for use in combustion chambers, the apparatus comprising an igniter consisting of co-axially mounted tubes with a central tube mounting an electrode coaxially therein, intermediate channels between coaxial outer tubes providing separate passages for fuel and air to a mixing chamber adjacent the electrode tip, said mixing chamber provided by a nozzle tip mounted on the end of the tubes at which the air and fuel meet at said electrode tip to produce a flame, said coaxial tubes being connected at an end opposite to said nozzle tip to a mounting flange and a housing containing a high voltage transformer, said concentric passageways for air and fuel being each connected to separate connecting means for air and fuel, said central tube containing the electrode being connected by concealed terminals to said high voltage transformer provided in said housing, a low tension electrical connecting means welded to said housing for connection of an electrical source to said high tension transformer, said coaxial tubes of said igniter being connectible to a combustion chamber wall so that the nozzle tip end thereof is inserted through said combustion chamber wall for providing a pilot flame to a main burner of said combustion chamber.

Full Text

The present invention relates to a pilot burner ignition apparatus for use in combustion chambers. Such an apparatus provides a continuous pilot flame in the combustion chamber leading to initial startup and protection against flame failure of main burner. Various designs of pilot burner ignition apparatus or systems are known to the prior art for use in combustion chambers. Most of the known prior art system have disadvantages. The prior art pilot burner fgnition apparatus or systems are less reliable and have fallen short of required standards as follows: 1. FAILURE OF ELECTRODE: Short circuiting of the electrode is found to be a common phenomenon due to e.g. deposition of dirt, soot and overflow of burning fuel, leading to failure of electrical insulation. Most of the existing devices employ electrode insulation made of small pieces of male/female insulation sleeves. While in operation any ingress of moisture reduces electrical insulation strength thereby causing failure of the electrode. Repair/replacement of the insulation sleeves is a costly affair and entails interruption in production. 2. IMPROPER ATOMIZATION: Flame failure occurs due to improper mixing by the fuel/air mixer. 3. HIGH-VOLTAGE IGNITION TRANSFORMER: Failure of High Voltage Transformer takes place due to failure of electrode insulation as well as faulty operation. It is a general practice to have the high voltage transformer kept at a safe distance from the combustion chamber and the igniter is connected by means of a high voltage electric cable. Frequent failures are observed in the high voltage cable and replacement thereof is a costly affair. All these defects in prior art pilot burner ignition apparatus or devices are sought to be overcome by the present invention. In other words, the pilot burner ignition apparatus of the present invention is provided with constructional features which overcomes the disadvantages listed above. Accordingly, it is an object of the present invention to provide: A specifically designed mixing chamber which achieves far better atomization and mixing of the fuel and air and which provides smooth flow of the fuel air mixture through the chamber; 2. A cartridge type maintenance free electrode made specially for the present construction; 3. An insulation which can withstand a high temperature and has a high strength is provided for the electrode enabling it to take temperatures of up to 1700°C. The insulation enables avoidance of short circuiting, resulting in high reliability; 4. An electronic design has been developed for the high voltage transformer which makes it short circuit protected, enables it to have a low weight, and higher reliability. The system can be used continuously and the electronic circuit of the transformer provides a high density current impulse to the induction coil and this in turn generates high voltage and high energy spark. 5. The high voltage transformer is attached to the ignitor. By this construction, no external high voltage electric cable is required. All high voltage parts including cable and transformer are totally enclosed and attached to the igniter. From the foregoing, it will be clear that the objects of the invention are achieved by the several novel features of the pilot burner ignition apparatus for use in combustion chambers and will enable trouble-free operation with high reliability. Accordingly, the present invention provides a pilot burner ignition apparatus for use in combustion chambers, the apparatus comprising an igniter consisting of co-axially mounted tubes with a central tube mounting an electrode coaxially therein, intermediate channels between coaxial outer tubes providing separate passages for fuel and air to a mixing chamber adjacent the electrode tip, said mixing chamber provided by a nozzle tip mounted on the end of the tubes at which the air and fuel meet at said electrode tip to produce a flame, said coaxial tubes being connected at an end opposite to said nozzle tip to a mounting flange and a housing containing a high voltage transformer, said concentric passageways for air and fuel being each connected to separate connecting means for air and fuel, said central tube containing the electrode being connected by concealed terminals to said high voltage transformer provided in said housing, a low tension electrical connecting means welded to said housing for connection of an electrical source to said high tension transformer, said coaxial tubes of said igniter being connectible to a combustion chamber wall so that the nozzle tip end thereof is inserted through said combustion chamber wall for providing a pilot flame to a main burner of said combustion chamber. The basic apparatus of the invention has three co-axial tubes welded to a common mounting flange. With the provision of concentric tubes separate channels for flow of fuel gas and air to the mixing chamber is facilitated. The central tube serves as the mount for the insulated electrode. To facilitate easy replacement of the electrode cartridge, the central tube is provided with threads at both ends. The terminal of the electrode with its high tension cable is concealed within a teflon bush in turn held in position with the help of a threaded metallic bush holder. The high voltage transformer is mounted inside a metallic housing. The housing is fixed with the bottom of the igniter by a pair of flanges. A flame proof low tension connection lug is welded to the body of the housing to provide electric supply. The mixing chamber is welded to the second and third outer tubes. A removable threaded flame tube is provided at the front end of the igniter. The electrode assembly consists of outer metallic tube with co-axial and concentric continuous ceramic sleeve. The electrode is passed through the ceramic sleeve. The electrode, ceramic sleeve and the outer metallic tube are cemented with refractory cement. In the accompanying drawings: FIG 1 . Depicts a general arrangement of the pilot burner ignition apparatus of the invention for use with a combustion chamber; FIG. 2 Illustrates a cross-sectional view showing details of the internal parts of the inventive apparatus; FIG. 3 Illustrates a cross-sectional view of the electrode cartridge. FIG. 4 Illustrates a housing for fixing high voltage transformer. Also illustrated are details of various features or parts shown in the major figures. In the preferred embodiment illustrated Figure 1 provides a general * external view of the pilot burner ignition apparatus to be affixed in an opening in a combustion chamber Flame tube 1A is where the fuel-air mixture comes into contact with the electrical spark and a flame is generated. Mounting flange IB facilitate mounting of the pilot burner ignition apparatus to an opening in a combustion chamber. Threaded coupling IE is welded to the fuel gas tube. An enlarged detail of flame tube 1A is shown in sheet 3 of the drawings. Similarly threaded coupling ID is welded to the air tube of the ignition apparatus. A pair of flanges IE facilitate fixing of the housing for the electronic spark ignition transformer. Housing IF accommodates the high voltage transformer inside. A flame-proof cable lug IG facilitates connection of a low tension electrical power connection to the transformer. An enlarged detail of flame-proof cable lug IG is shown below Figure 1. Figure 2 illustrates in cross-section igniter shown in Figure 1. At 2A is the nozzle tip through which atomized fuel-air mixture passes through to burn in the flame tube 1A. At 2B is the fixed nozzle welded to the fuel gas tube and air tube. 2C indicates the nut for clamping the electrode cartridge in position. 2D is the adapter or bush holder for clamping bush 2E in position. Bush 2E is made of insulating material and accommodates electrical wire terminals therein. 2F indicates the two separate threaded couplings for air and fuel to the respective air and fuel channels between concentric tubes. Enlarged detailed views of couplings 2A, 2B, 2C, adapter 2D and bush 2E are shown in the drawings. Also shown are cross-sectional views at Y-Y and Z-Z of igniter tubes and electrode cartridge respectively. Figure 3 illustrates only the inner tube with the electrode cartridge. At both ends of the tube there are threads provided. At one end, the cartridge is fitted to the adapter 2D with the help of nut 2C. The other end of the threaded tube holds the nozzle tip 2B. Within the inner most tube holding the electrode, is a refractory sleeve 3A which electrically insulates the electrode 3B. Figure 4 illustrates a housing for accommodating the high voltage transformer. Output of the transformer is connected to electrode 3B. Although the invention has been shown and described with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that various changes, omissions, and additions may be made therein and thereto, without departing from the spirit and scope of the invention. WE CLAIM: 1. A pilot burner ignition apparatus for use in combustion chambers, the apparatus comprising an igniter consisting of co-axially mounted tubes with a central tube mounting an electrode coaxially therein, intermediate channels between coaxial outer tubes providing separate passages for fuel and air to a mixing chamber adjacent the electrode tip, said mixing chamber provided by a nozzle tip mounted on the end of the tubes at which the air and fuel meet at said electrode tip to produce a flame, said coaxial tubes being connected at an end opposite to said nozzle tip to a mounting flange and a housing containing a high voltage transformer, said concentric passageways for air and fuel being each connected to separate connecting means for air and fuel, said central tube containing the electrode being connected by concealed terminals to said high voltage transformer provided in said housing, a low tension electrical connecting means welded to said housing for connection of an electrical source to said high tension transformer, said coaxial tubes of said igniter being connectible to a combustion chamber wall so that the nozzle tip end thereof is inserted through said combustion chamber wall for providing a pilot flame to a main burner of said combustion chamber. 2. The apparatus as claimed in Claim 1 wherein said central tube is an electrode cartridge having encased within said tube a refractory sleeve which electrically insulates said electrode therewithin, said end of said electrical cartridge opposite said electrode tip having threads whereby said electrode cartridge is threadedly connected to an adapter and nut combination, a bush being clamped between said adapter and said housing, said housing having a flange also clamped to said mounting flange, two said outer coaxial tubes providing separate channels for said air and said fuel being fixed to said mounting flange, said concentric tubes being of high grade, high temperature strength metal, a wall mounting flange also welded to said outer tubes between said nozzle tip and said connection means for air and fuel and said housing for said transformer, said wall mounting flange being connectible to opening in a wall of said combustion chamber 'through which the igniter nozzle is inserted to supply a pilot flame to said main burner. 3. The apparatus as claimed in any of claims 1 and 2, wherein said electrode tube holder or cartridge is provided at its end adjacent the electrode tip with threads for the male/female threaded connection of said nozzle tip, said nozzle tip having oriented holes therethrough which cause atomization of fuel gas and air to the mixing chamber to enable burning. 4. The apparatus as claimed in any of claims 1 to 3 wherein said connection means for said gas and fuel are threaded couplings separately connected to said air and fuel passageways between respective concentric metal tubes. 5. A pilot burner ignition apparatus for use in combustion chambers substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

827-del-1998-abstract.pdf

827-del-1998-claims.pdf

827-del-1998-correspondence-others.pdf

827-del-1998-correspondence-po.pdf

827-del-1998-description (complete).pdf

827-del-1998-drawings.pdf

827-del-1998-form-1.pdf

827-del-1998-form-19.pdf

827-del-1998-form-2.pdf

827-del-1998-form-4.pdf

827-del-1998-gpa.pdf