Abstract:
Methods and apparatus are presented for producing carbon black on a substrate. One preferred method includes providing a head assembly including a nozzle, the nozzle including a first injector for injecting a gas such as acetylene, and a second injector for injecting a mixture of a fuel and an oxidant to produce a pilot flame. The head assembly is indexed over a substrate on which is to be deposited carbon black. The acetylene is injected through the first injector, then through a pilot flame emitted from one or more second injectors, and finally toward a substrate to be coated with carbon black, but only when a deposit of carbon black is desired. The method includes ceasing the flow of acetylene, indexing the head assembly away from the substrate on which was just deposited the carbon black after a carbon black deposition sequence, and ceasing fuel gas and oxidant gas flows through the second injector. Just before the next carbon black deposition is required, the fuel and oxidant are initiated and ignited with an ignition source and accompanying automatic electronic ignition, thus recreating the pilot flame(s). Indexing the head assembly toward a surface to be coated with carbon black, and initiating a flow of acetylene when a layer of carbon black is desired, completes a cycle.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) to provisional application No. 60/199,554, filed Apr. 25, 2000, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Brief Description of the Invention 
     The present invention relates to combustion methods and apparatus, more particularly, those that produce carbon black. 
     2. Related Art 
     Previously, it has been known to produce carbon black by use of a flame, through which a highly-carbon-laden gas, such as acetylene, was moved through. The heat of the flame “cracks” the acetylene and forms the carbon black. 
     Improvements have been made by some, for example, to eliminate the flame, sometimes called a pilot flame. Elimination of the pilot flame does eliminate two gases, fuel (typically natural gas) and oxidant (typically air or oxygen) for the pilot flame. Normally what is done is that an ignition source is placed near the acetylene flow. When a carbon black deposit is desired, an ignition source is activated, lighting off the acetylene. 
     This approach has its own drawbacks however, the main one being that the ignition source is exposed to the source of carbon black. The carbon black can and does tend to cloak the ignition source in carbon black. 
     What is desired then, is a method and apparatus which eliminates or greatly reduces the amount of carbon black deposited on ignition sources, but which maintains the benefits of the pilot flame. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, methods and apparatus are presented which greatly reduce, or even eliminate, the above problems of carbon black deposited on the ignition source, while maintaining the benefits of a pilot flame. 
     In a first aspect of the invention, an apparatus is presented, the apparatus comprising a nozzle including a first-injector for injecting a highly-carbon-laden gas. The nozzle includes at least one second injector for injecting a mixture of a fuel and an oxidant for a pilot flame, the nozzle secured in a moveable head assembly. The head assembly comprises a main gas block and an ignition source mounted in a plenum which encloses respective tips of the first and second injectors. The highly-carbon-laden gas and the fuel and oxidant mixture exit through these tips and enter and fill the gas plenum, as further described herein. 
     As used herein, the term “highly-carbon-laden gas” means a gas as previously defined in U.S. Re. Pat. No. 34,785: a gaseous hydrocarbon or mixture of gaseous hydrocarbons comprising at least 15% of a constituent in respect of which the ratio of the number of carbon atoms to the number of hydrogen atoms C/H is greater than 0.75. 
     In the second aspect of the invention, methods are presented for producing carbon black on a substrate. One preferred method includes the steps comprising providing a head assembly including a nozzle, the nozzle including a first injector for injecting a highly-carbon-laden gas, and a second injector for injecting a mixture of a fuel and an oxidant to produce a pilot flame; indexing a head assembly (“indexing” is a term of art meaning precisely positioning) over a substrate on which is to be deposited carbon black, flowing the highly-carbon-laden gas through the first injector, then through a pilot flame emitted from the second injector (preferably there exists more than one second injector), and finally toward a substrate to be coated with carbon black, but only when a deposit of carbon black is desired. The method further comprises ceasing the flow of highly-carbon-laden gas, indexing the nozzle away from the substrate on which was just deposited the carbon black after a carbon black deposition sequence, and ceasing fuel gas and oxidant gas flows through the second injector. Purge gas (nitrogen, for example) is used to keep the first and/or second injectors clean, and to help cool each nozzle. Just before the next carbon black deposition is required, the method comprises initiating the fuel and oxidant preferably through a deflector jet as described herein, and igniting both with an ignition source, thus recreating the pilot flame(s). Indexing the head assembly toward a surface to be coated with carbon black, and initiating a flow of highly-carbon-laden gas when a layer of carbon black is desired, completes a cycle. 
     Contrary to previous apparatus and methods known in the art, the ignition source and timing sequence allow reduced operating cost on production runs where carbon deposition is required infrequently. This is performed by an ignition system that will activate the pilot flame at least one cycle before the firing cycle, and deactivate the flame immediately following the scheduled application of carbon black. 
     Another aspect of the invention is that the nozzle is preferably removable, more preferably by simply using a wrench or simple tool to loosen a nut securing the nozzle to the head assembly. This feature allows for ease of replacement of individual nozzles. As used herein, the word “nozzle” means one or more components of a head assembly which directs the highly-carbon-laden gas, and oxidant and fuel, into a plenum, as is further described herein. This “removable” (preferably quick change) nozzle feature enables an operator to quickly change out dirty or damaged nozzles, preferably in less than 60 seconds, while the head assembly remains otherwise undisturbed, indexed in position, for example on an IS glass molding machine. In a preferred embodiment, the nozzle comprises: 
     a) a substantially hollow, substantially cylindrical body having a gas exit end and a connection end, the gas exit end having an end cap having a central orifice and at least one non-central orifice, the central orifice having positioned therein a hollow tube having it first end extending into the central orifice and a second end extending into the substantially hollow, substantially cylindrical body, the second end of the hollow tube being supported by and extending through a support plate positioned in an interior location of the substantially hollow, substantially cylindrical body, the connection end of the substantially hollow, substantially cylindrical body adapted to be mated with a sealing member when the nozzle is installed for use; 
     b) the support plate positioned to divide the interior of the substantially hollow, substantially cylindrical body into a first chamber and a second chamber, the first chamber defined by the support plate, end cap, and a first interior surface of the substantially hollow, substantially cylindrical body, the second chamber defined by the support plate, sealing member, and a second interior surface of the substantially hollow, substantially cylindrical body; 
     c) the substantially hollow, substantially cylindrical body having at least one orifice extending from an exterior surface of the body to the first chamber, and at least one orifice extending from the exterior surface of the body to the second chamber. 
     Another aspect of the invention is a removable, preferably quick change head assembly. As used herein, the term “head assembly” means an assembly which includes a main gas block having means for securing one or more nozzles, and having internal channels or conduits for flow of fuel, oxidant, and highly-carbon-laden gas. There is also preferably a conduit or channel in the main gas block for a purge gas such as nitrogen or air. Each head assembly is equipped with at least two gas supply connections: one for highly-carbon-laden gas, and one for mixture of fuel and oxidant for a pilot flame. Preferably, the head assembly has a third gas supply connection for purge gas. (Variations may be made by those skilled in the art; for example, four gas connections (one for fuel, one for oxidant, one for highly-carbon-laden gas, and one for purge gas) may increase complexity, but this is compensated by increased safety.) The gas supply connections are preferably connected to gas supply conduits (preferably stainless steel braided TEFLON® or metal conduits) which are connected in turn to a gas distribution block, which is plumbed preferably in close proximity to the head assembly. Each gas distribution block is preferably equipped with quick disconnects, preferably color-coded, which connect to the gas supply conduits. Each disconnect is preferably color-coded to prohibit incorrect recoupling of the respective gas conduits. The quick disconnects require no tools to couple and uncouple the gas supply conduits, 
     Preferably, head assemblies of the invention are attached to an inventive funnel arm shaft clamp block by way of a single lock nut, which slides easily in and out of a T-slot. The single lock nut design provides for a complete head assembly change over in minutes, and the T-slot mounting ensures fast, dependable realignment. 
     Another aspect of the invention is a head assembly mounting plate which mates on one of its main surfaces with the T-slot of the inventive funnel arm shaft clamp block, and on its other main surface with a main gas block. The inventive head assembly mounting plate comprises a T-shaped tongue portion that serves to position the head assembly on the funnel arm shaft clamp block of the IS machine. By off-setting bolt holes from a center line of the mounting plate, this apparatus can achieve a wider range of vertical adjustment by simply rotating the plate 180° and reattaching it to the head assembly. In many cases, this will allow customer job changes from a short blank to a large blank without the need to reposition customer&#39;s funnel arm shaft clamp block which sets critical alignment. 
     A still further aspect of the invention is a funnel arm shaft clamp block with height adjustment. This feature comprises a funnel arm shaft clamp block which cooperates with, but is independent of the inventive head assembly. When properly positioned, the inventive funnel arm shaft clamp, block will remain with the funnel arm shaft, when, for example, a head assembly change is desired. With the inventive funnel arm shaft clamp block left undisturbed, the head assembly can be changed out in minutes and a new head assembly will be properly positioned or “indexed” simply by securing the single quick change nut. Funnel arm shaft clamp blocks of the invention allows for simple height adjustments or the complete replacement of a head assembly without the loss of critical nozzle to mold blank alignment, important for many reasons in I.S. machines. 
     A further aspect of the invention includes a pre- and post-purge system, for when the highly-carbon-laden gas is processed to produce carbon black. When the acetylene or other highly-carbon-laden gas is on and flowing, it is passed through an oxy-fuel flame or air-fuel flame, which is commonly known as a pilot flame. Preferably to ensure system safety and minimize the deposition of carbon black on the outlet face of an injector, nitrogen or some other gas (even air) is preferably used to purge the acetylene conduit and pilot gas conduits through the injector conduits, preferably before and after each carbon black deposition cycle. 
     Another aspect of the invention is an automatic ignition system. This system comprises electronics and a spark source that will activate the pilot flame(s), preferably at least one cycle before the firing cycle, and deactivate the pilot flame(s) at a predetermined time, preferably immediately, following the scheduled application of carbon black. This greatly reduces operating costs on production runs where carbon deposition is required infrequently. 
     A further aspect of the invention is a shield surrounding the tips of the one or more nozzles and their associated injectors, in a fashion which has multiple functions, one of which is to serve as a flash shield to minimize visible flash to the operator. The cracking of acetylene and other highly-carbon-laden gases emits a very bright yellow-white flash of light as the acetylene is fired through the pilot flame. The inventive shield minimizes this visible flash. This device also serves to insulate the pilot flames from the occasional blow out due to the intense air drafts sometimes generated by cooling air used on typical IS machines. Yet another function of this inventive shield is to serve as four sides of a plenum which is completed when the head assembly is indexed away from the mold blanks and put in a resting position. The inventive shield moves over and aligns with a shelf plate and thus forms an enclosure or plenum which forms an ignition chamber for the inventive ignition system. When it is desired to light the pilot flames, pilot fuel and oxidant flow are initiated by the inventive automatic ignition system to fill the plenum. After a short time the ignition system ignites a spark source and the gases in the plenum are ignited, in turn igniting the pilot gases emanating from one or more injectors in the head assembly. 
     A final feature of the invention is a blow and blow delivery arm. On standard IS machines, there are two basic processes: “press and blow” which does not use a funnel to guide the gob into the mold blank, and: “blow and blow” which does require the use of a funnel. In the known “press and blow” process, systems known under the trade designation “ALBLACK™”, available from L&#39;Air Liquide SA, Paris, France, and Air Liquide America Corporation, Houston, Tex., take advantage of an available funnel arm shaft to mount the hardware for the production of carbon black when needed. On “blow and blow” processes, however, a more sophisticated retractable delivery system was designed in accordance with the present invention to work with a working funnel, and yet still mount on the same shaft. This was accomplished in the present invention by using the same universal funnel arm shaft clamp block, but incorporating an air activated latching device to engage the burner head assembly as required and a release that will allow it to retract so as not to interfere with the gob drop. The system of the invention incorporates all of the same features as the “press and blow” system including the quick change capabilities. 
     Further advantages of the main features of the invention will become apparent upon reading the Brief Description of Drawings and Description of Preferred Embodiments which follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a 3 gob head assembly in accordance with the present invention, showing the position of the head assembly when carbon black deposition is not required; 
         FIG. 2  is a perspective view as in  FIG. 1 , showing a 3 gob head assembly of the invention when carbon black deposition is required; 
         FIG. 3  is a perspective view of a nozzle and associated injectors in accordance with the present invention; 
         FIG. 4  is another perspective view of a 3 gob head assembly in accordance with the invention; 
         FIG. 5  is a reverse plan view of a head assembly of the present invention, showing an ignition source installed; 
         FIGS. 6   a  and  6   b  are perspective views, with some components in phantom, of a head assembly mounting plate in accordance with the present invention; 
         FIG. 7  is a perspective view of a funnel arm shaft clamp block with height adjustment in accordance with the present invention; 
         FIG. 8  is a logic diagram of an automatic ignition system in accordance with the present invention; 
         FIG. 9  is a perspective view of a shield and a shelf in accordance with the invention, forming part of a gas plenum; 
         FIGS. 10 and 11  are perspective views, with parts cut away, of one embodiment of a main gas block in accordance with the present invention; 
         FIGS. 12 ,  13 , and  14  are plan, side elevation, and end elevation views, respectively, with some parts in phantom, of a main gas block in accordance with the invention; 
         FIG. 15  is a side elevation view of an embodiment of a hole machined in the main gas block of FIGS.  12 , 13 , and  14 ; and 
         FIGS. 16 and 17  are cross-sectional and end elevation views, respectively, of a nozzle in accordance with the invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Note that while the drawings are deemed to be representative of preferred embodiments, they are not necessarily to scale. 
       FIGS. 1 and 2  illustrate the primary features of the present invention. Illustrated in  FIG. 1  is an apparatus of the invention  2  which includes a head assembly  4 , having a shield  6  attached to the bottom thereof. Shield  6  is preferably a hollow, four sided rectangle (although other shapes, such as cylindrical may be employed), which may be made of sheet metal or other type of rigid, noncombustible material. Also illustrated is a shelf plate  8  which is positioned underneath the shield  6  and which may or may not touch the bottom edge of shield  6 . Shelf plate  8  and shield  6 , along with a lower surface of head assembly  4 , essentially create a plenum or gas box, as will be explained later herein. Further illustrated in  FIG. 1  are three identical nozzles indicated at  10  (where  FIG. 1  illustrates only a top portion of the nozzles). A perspective view of a nozzle is indicated in FIG.  3 . Nozzles  10  extend from a top surface of a main gas block  18 , down through said main gas block  18  vertically, as will become more apparent herein. Also included in the apparatus  2  of  FIG. 1  is a gas distribution block  20 , and gas hoses  22 ,  24 , and  26 . For example, gas hose  22  may be a purged gas hose, wherein a purge gas such as nitrogen or even air may be used. Gas hose  24  will typically carry a mixture of fuel gas and oxidant, such as a mixture of natural gas and oxygen, while gas hose  26  carries a highly-carbon-laden gas such as acetylene, propylene-acetylene mixture, and the like. Main gas block  18  is attached to a funnel arm shaft  12  via a funnel arm shaft clamp block  14  and a head assembly mounting plate  16 . Completing  FIGS. 1 and 2  are molds  28 , which as is well known in the art would receive a molten gob of glass. Also depicted in  FIG. 1  on the shield  6  are holes  30  which may be termed cooling vents, although they have multiple purposes as further explained herein. 
       FIG. 1  represents the position of the apparatus when carbon black is not being deposited in molds  28 , whereas  FIG. 2  indicates a position of the apparatus wherein carbon black is being deposited in molds  28 , as depicted by flames  32 . Flames  32  from the highly-carbon laden gas are typically only flowing for a short period of time (usually a matter of seconds or less). In order to move from the position of  FIG. 1  to the position of  FIG. 2 , the main gas block  18 , head assembly mounting plate  16  and funnel arm shaft clamp block  14  are pivoted or indexed about the funnel arm shaft  12  in order to move the main gas block  18  and head assembly  4 , with its corresponding shield  6 , over the molds. The indexing of the apparatus back and forth between the positions of  FIGS. 1 and 2  are preferably performed by automatic controls associated with an IS machine, which is not shown in the figures and is not a part of the invention. Flames  32  are fired in an automatic ignition system of the invention as further explained herein. 
     As previously mentioned,  FIG. 3  illustrates in perspective one embodiment of a nozzle  10  in accordance with the present invention. Nozzle  10  comprises a metallic body  11  preferably composed of steel, although other metals such as brass will function effectively. Nozzle  10  includes a central or first injector  38  which protrudes preferably a certain distance away from a hot face  39  of nozzle body  11 . The distance of protrusion of ejector  38  away from hot face  39  depends on conditions of firing, the gases used for the highly-carbon laden gas, the number of firings and a number of other parameters. The distance may range from 0 (i.e. flush) to 5 cm, more preferably from about 1 cm to 5 cm. First injector  38  extends inward into nozzle body  11  about half of the length of nozzle body  11 , which allows flow of highly-carbon-laden gas flowing through main gas block  18  to traverse through a hole  52  and then exit first injector  38  at its tip. First injector  38  is essentially a metal tube, preferably steel, which fits snugly in a centrally drilled or machined through hole in nozzle  10  body. Also illustrated are three second injectors  40  which are preferably equidistantly placed about the centrally located first injector  38 . Second injectors  40  are the so-called pilot flame injectors, where a mixture of a fuel gas and an oxidant, preferably natural gas or methane and oxygen are flowed through and ignited to form a hot flame through which the highly carbon-laden gas will flow. Second injectors  40  are preferably metallic tubes fitting snugly into respective through holes in nozzle body  11 , extending roughly one third of the length of nozzle body  11 . Second injectors receive a feed of fuel and oxidant mixture through a hole (not shown in  FIG. 3 , but just behind flange  48 )) in nozzle body  11 . 
     Referring to  FIGS. 16 and 17 , nozzle  10  includes a quick change bolt  42 , which has a male portion  251  having threads and adapted to extend into a cavity  252  in nozzle body  11 . Cavity  252  has internal female threading  250  that mate threads on male portion  251 . Bolt  42  preferably has metallurgy same or similar as nozzle body  11 . Bolt  42  is inserted into the top of main gas block  18  and engages nozzle body  11 , which is inserted from an underside of main gas block  18 , through shield  6 . A flange  48  is included in the nozzle  10  which serves to seal the previously described plenum formed by shield  6  and shelf plate  8 . Also indicated in  FIG. 16  are holes  50 ,  52 , and  55 , hole  50  being an inlet for purge gas, such as nitrogen or air, hole  52  allows a flow of acetylene or other highly carbon-laden gas to first injector  38 , and hole  55  allowing a flow of fuel/oxidant mixture to second injectors  40 . Also illustrated in  FIG. 16  is the extension of first injector  38  into the nozzle body  11  and through a support plate  254 , which seals off the fuel/oxidant mixture from the acetylene.  FIG. 17  illustrates the hot face  39 , first injector  38 , and second injectors  40  (three in this embodiment). At least one second injector must be present, while more than three are possible, although adding to cost and complexity. 
     When assembling a nozzle  10  into a main gas block  18 , o-ring gaskets are used. This use of o-rings is a standard technique and requires no further explanation to the skilled artisan. The rubber material known under the trade designation VITON™ is a preferred o-ring material. 
       FIG. 4  illustrates in perspective view a head assembly  4  in accordance with the present invention, again illustrating a shield  6  and three nozzles  10 . 
       FIG. 5  is a reverse plan view, looking from an underside of the shield  6  of the apparatus of FIG.  4 . Three nozzles  10  may be clearly seen protruding from main gas block  18  and into the interior space of shield  6 , through three respective holes  47  in shield  6 . Shield  6  is secured to main gas body  18  via bolts  45   a  and  45   b.    
     The reverse plan view of  FIG. 5  is convenient for illustrating an igniter means  34 , shown here as a common spark plug, which protrudes through one side of shield  6 , the hot end of spark plug  34  protruding into the interior space of the shield  6 . For the igniter to work, several problems had to be solved. 
     1) The igniter had to be isolated from the extreme temperatures generated by the pilot flames. 
     2) Minimize carbon deposition on the electrode and ground of the igniter. 
     3) Overcome the physics of high velocity gas/oxygen pilot flame during ignition. These objectives were substantially obtained by providing one or more deflector jets  36 , which are installed at strategic points between burner nozzles. Deflector jet  36  is tapped into the conduit that supplies gas/oxygen mixture to the pilot flames. These deflector jets serve to divert and retard the rate of a small sample of gas/oxygen flow and present the small sample to the igniter at a rate where the igniter would be effective, but not in direct line with the pilot flames. Igniter  34  is connected to electronics (not illustrated) which allow automatic firing of the igniter  34  in a sequence to be described herein. For the moment, it is important to point out that igniter  34  serves to ignite combustible gases which fill the interior space or plenum within shield  6  at an appropriate time to light the pilot flames emanating from second injectors  40 . This is critical in that gases which comprise the pilot flames may be shut off when not needed, and reinitiated when needed. Without shield  6  and accompanying shelf plate  8  as previously described, as well as deflector jet  36 , reignition of the pilot flames would be difficult, if not impossible, given the heavy air drafts in a typical glass manufacturing plant. Furthermore, the pilot flames may be lit usually in one or two ignitions of igniter  34 . Ignition may be verified by viewing the pilot flames through the holes  30 . 
     Turning now to  FIGS. 6   a  and  6   b ,  FIG. 6   a  is a perspective view funnel arm shaft clamp block  14  and its accompanying head assembly mounting plate  16  in accordance with the present invention. Main gas block  18  and gas hoses are shown in phantom in  FIG. 6   a  for clarification. Head assembly mounting plate  16  includes a tongue  54  which protrudes into a T-slot  60 . Also depicted are a mounting nut  56  for attaching and tightening head assembly mounting plate  16  to the funnel arm shaft clamp block  14 . Mounting nut  56  operates with an engaging nut  58  as is illustrated in  FIG. 6   b , wherein nut  56  is tightened to firmly attach mounting plate  16  to clamp block  14 . Also illustrated in  FIG. 6   a  is a rectangular slot  62  which receives engaging nut  58  as illustrated in  FIG. 6   b.    
     Shaft clamp block  14  essentially comprises two halves  14   a  and  14   b  which are primarily secured together using a pair of bolts  55   a  and  55   b  which traverse through both block halves  14   a  and  14   b . Shaft clamp block  14  is allowed to pivot around shaft  12  by loosening matching clamp block clamp halves  68   a  and  68   b  via a clamp block bolt  66 . As may be seen in the perspective view in  FIG. 7  of the clamp block and its assembly, clamp block clamp halves  68   a  and  68   b  are secured using a clamp block nut  70  which engages clamp block bolt  66  in order to tighten the clamp block onto shaft  12 . Clamp block  14  is preferably only so tight on shaft  12  to support the main gas block  18 , but allowing for indexing or movement as depicted in  FIGS. 1 and 2 . A shaft block hole  72  is depicted in  FIG. 7 , the hole  72  accommodating shaft  12 . 
       FIG. 9  is a further perspective view of a triple gob set up, again showing nozzles  10 , head assembly  4  and shield  6  in association with a shelf plate  8 . Once again, the function of shield  6  and shelf plate  8  primarily is to create a plenum for combustible gases so that the pilot flames may be easily lit by igniter  34  (not shown in FIG.  9 ). The shield also has a secondary function which is to shield an operator&#39;s eyes from the bright yellow flame of acetylene when the acetylene is fired for carbon black deposition. Cooling vents  30  are shown circular, but of course, could be rectangular or even slits without departing from the scope of the invention. Shield  6  and shelf plate, while preferably being sheet metal, which is steel material, could conceivably be any non-combustible heat resistant material, such as asbestos or other flame retardant material. 
       FIGS. 10 and 11  illustrate in perspective view a main gas block  18  having three through holes  106 ,  108 , and  110 , in a header portion  19 . Holes  106 ,  108 , and  110  are drilled or machined for accepting three respective nozzles, not shown for clarity. A support section of main gas block  18  includes in this embodiment three drilled or machined vertical conduits  100 ,  102 , and  104 . Conduits  100 ,  102 , and  104  preferably do not traverse the entire thickness of support section  17 , although they may be drilled all the way through section  17 , then capped with an appropriate screw or other fitting. A third set of drilled or machined conduits  112 ,  114 , and  116  are depicted, travelling length-wise, in roughly horizontal attitude. Conduits  112 ,  114 , and  116  intersect with conduits  124 , 126 , and  128 , which also traverse roughly main gas block  18  in roughly horizontal manner. 
     Nitrogen, or other purge gas, will preferably flow (when called for) through conduits  100 , 124  and  112 . Acetylene, or other highly-carbon-laden gas will flow when called for through conduits  102 ,  126 , then  114 . Finally, oxidant-fuel mixture is adapted to flow through conduits  104 , 128 , and  116  when called for. 
     In  FIG. 10 , one can see in perspective an illustration of a set of machined or drilled surfaces associated with conduit  108 . Hole  118  accepts purge gas from conduit  112 ; hole  120  accepts acetylene from conduit  114 ; and hole  122  accepts mixture of fuel and oxidant form conduit  116 . Holes  118 ,  120 , and  122  are orifices sized accordance with the desired flow rates and pressures of the gases flowing there through. Each of holes  110  and  106  will have orifices for accepting flow of gases in similar fashion, and will be sized accordingly. It is important that the orifices are matched so that one nozzle receives more or less the same amount of pilot gases, for example, as the other nozzles, in instances where there is more than one nozzle. Of course, the apparatus of the invention is not limited to three gob systems. One gob, two gob, three gob, and four gob systems are quite common; however there is no reason one could not have more than four nozzles, as the principles of the invention are equally applicable. 
       FIGS. 12-15  illustrate features of another embodiment of a main gas block  200  of the invention. Referring first to the plan view of  FIG. 12 , holes  206 ,  208 , and  210  are provided to accommodate respective nozzles (not shown). Conduits  201 ,  202 , and  204  allow flows of purge gas, highly-carbon laden gas, and fuel/oxidant mixture, respectively, to enter main gas block  200 . These gases then proceed through conduits  224 ,  226  and  228 , respectively, through support portion  217 . Conduit  224  is preferably position in support portion  217  to intersect with conduit  212 ; conduit  226  is position to intersect with conduit  214 ; and conduit  228  is positioned to intersect with conduit  216 . Purge gas may then traverse from the conduit  212  to conduits  236  and  238 , through conduit  230 , and into nozzle(s)  10  through respective orifice  50  (see FIG.  16 ). Highly-carbon-laden gas may traverse conduit  236  to conduit  214 , proceed through conduits  240  and  242  (FIG.  13 ), and through conduit  232  and into nozzle(s)  10  through respective orifice  52 . Mixture of fuel and oxidant proceeds through conduit  228 , through conduit  216 ,  244 ,  246  and  234 , and finally into respective orifice  55  in nozzle(s)  10 . 
       FIG. 8  is a logic diagram of an automatic ignition sequence in accordance with the present invention. When the automatic ignition system is engaged, typically the head assembly is over shelf plate  8  with the pilot flames off and nitrogen flow on as indicated at  74 . The electronic controls of the IS machine, which are not part of the invention, then ask at some point during the glass molding process if a mold lubrication is needed, which is indicated at  76 . If the answer is yes, the sequence proceeds to initiate fuel and oxidant flow to the plenum. This is indicated at  78  in  FIG. 8. A  short time later, usually a matter of seconds, the igniter  34  is discharged as indicated at  80  and the acetylene is discharged, depositing a layer of carbon black on the internals of the molds as indicated in FIG.  2 . In a matter of seconds or less, the acetylene is deactivated and the nitrogen flow resumed, as indicated at  88 , the head assembly is indexed back over the shelf plate  8 , and the flow of fuel and oxidant is ceased, as indicated in the box  90 . Logic sequence then reverts back to the first step  74 . 
     This unique and inventive automatic ignition system was devised after it was noticed that in some glass molding operations, the molds need not be lubricated for every glass gob dropped into the mold; indeed, it was determined that in some cases up to 50 glass gobs could be dropped into molds  28  before the molds needed to be relubricated with carbon black. Reduced need to lubricate the molds has advantages, but also presents a challenge in how to conserve fuel and oxidant for the pilot flames. Fuel and oxidant can only be conserved if their flow is minimized or turned off, and then when needed, they can be reinitiated and the pilot flames ignited in a manner providing the operator with a certain degree of confidence that this will occur without fail. Failure of the pilots to light would be very disadvantageous because of the need to deposit carbon black into the molds, which must not fail. If the carbon black is not deposited, the blank molds could be damaged which would cause a shut down of at least a section of the IS machine for replacement of the molds. 
     The above description of preferred embodiments is meant to be exemplary only and is not exhaustive of all variations which may be apparent to those of skill in the art, which are considered within the scope of the invention and the appended claims. For example, another embodiment may be employed if excessive carbon is built-up on the igniter (this has not been the case to date). A reduced purge gas flow through a “cooling collar” can be employed that shields the electrode and ground area of the spark plug or other igniter with a controlled blast of purge gas while the acetylene is firing.