Abstract:
A head assembly for a radiant burner, an inlet assembly and a method are disclosed. The head assembly is for a radiant burner. The head assembly may include a housing defining a plurality of identical housing apertures extending therethrough, an insulator received by the housing and defining a corresponding plurality of identical, complimentarily-located insulator apertures extending therethrough, and at least one inlet assembly configured to be received by one of the identical housing apertures. Each inlet assembly may include a housing portion configured to be received by the one of the identical housing apertures, and an insulator portion configured to fill the complimentarily-located insulator aperture. In this way, a head assembly is provided which has a number of apertures, any of which may receive an inlet assembly. Given that each inlet assembly is configured to be received by any of the apertures, this provides flexibility for the insertion and removal of the assemblies, without needing to completely disassemble the head assembly from the radiant burner. Also, by forming the inlet assembly with a housing portion and insulation portion, the assembly can be located within the head assembly and the insulating portion prevents heat damage.

Description:
[0001]    This application is a national stage entry under 35 U.S.C. §371 of International Application No. PCT/GB2014/051841, filed Jun. 16, 2014, the entire content of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a head assembly for a radiant burner, an inlet assembly and a method. 
       BACKGROUND 
       [0003]    Radiant burners are known and are typically used for treating an effluent gas stream from a manufacturing process tool used in, for example, the semiconductor or flat panel display manufacturing industry. During such manufacturing, residual perfluorinated compounds (PFCs) and other compounds exist in the effluent gas stream pumped from the process tool. PFCs are difficult to remove from the effluent gas and their release into the environment is undesirable because they are known to have relatively high greenhouse activity. 
         [0004]    Known radiant burners use combustion to remove the PFCs and other compounds from the effluent gas stream. Typically, the effluent gas stream is a nitrogen stream containing PFCs and other compounds. A fuel gas is mixed with the effluent gas stream and that gas stream mixture is conveyed into a combustion chamber that is laterally surrounded by the exit surface of a foraminous gas burner. Fuel gas and air are simultaneously supplied to the foraminous burner to affect flameless combustion at the exit surface, with the amount of air passing through the foraminous burner being sufficient to consume not only the fuel gas supplied to the burner, but also all the combustibles in the gas stream mixture injected into the combustion chamber. 
         [0005]    The range of compounds present in the effluent gas stream and the flow characteristics of that effluent gas stream can vary from process tool to process tool, and so the range of fuel gas and air, together with other gases or fluids that need to be introduced into the radiant burner will also vary. 
         [0006]    Although techniques exist for processing the effluent gas stream, they each have their own shortcomings. Accordingly, it is desired to provide an improved technique for processing an effluent gas stream. 
       SUMMARY 
       [0007]    According to a first aspect, there is provided a head assembly for a radiant burner, the head assembly comprising: a housing defining a plurality of identical housing apertures extending therethrough; an insulator received by the housing and defining a corresponding plurality of identical, complimentarily-located insulator apertures extending therethrough; and at least one inlet assembly configured to be received by one of the identical housing apertures, each inlet) assembly comprising: a housing portion configured to be received by the one of the identical housing apertures; and an insulator portion configured to fill the complimentarily-located insulator aperture. 
         [0008]    The first aspect recognises that as the range of effluent gases to be processed increases, the possible ranges of configurations for the radiant burner also increases. In particular, different types of effluent gases to be processed may be provided at different rates and in different concentrations. In order to abate or process these different effluent gases, these different effluent gases may need to be distributed in different ways into the combustion chamber of the radiant burner, together with different combinations, concentrations and/or rates of other fluids such as fuel, an oxidant and any other supporting fluids such as for example, air. These varying requirements can lead to complex engineering of the head assembly and the conventional approach is to create a head assembly for each particular application. This complexity is exacerbated by the relatively small size of the radiant burner and it can become complicated to provide for all the necessary couplings and routing of the necessary conduits in order to convey, mix and/or distribute the fluids to the appropriate outlets feeding the combustion chamber. The first aspect also recognises that reconfiguring existing head assemblies to meet these different requirements can be difficult and even impossible, as can be performing maintenance without completely dissembling the radiant burner. This can be extremely disruptive, particularly when some parts of the head assembly require more regular maintenance than others. 
         [0009]    Accordingly, a head assembly may be provided. The head assembly may be for a radiant burner. The head assembly may comprise a housing. The housing may define or provide a plurality of housing apertures, each of which may be identical. The housing apertures may extend through the housing. The head assembly may also comprise an insulator. The insulator may be received by the housing. The insulator may define or provide a corresponding plurality of identical insulator apertures. Those insulator apertures may be complementarily or co-located with the housing apertures. The insulator apertures may extend through the insulator. The head assembly may also comprise at least one inlet assembly. The inlet assembly may be configured or dimensioned to be received by, or located in, one of the housing apertures. Each of the inlet assemblies may comprise a housing portion. The housing portion may be configured or dimensioned to be received by the housing aperture. The inlet assembly may also comprise an insulator portion. The insulator portion may be shaped, dimensioned or configured to fill or occupy the insulator aperture. In this way, a head assembly is provided which has a number of apertures, any of which may receive an inlet assembly. Given that each inlet assembly is configured to be received by any of the apertures, this provides flexibility for the insertion and removal of the assemblies, without needing to completely disassemble the head assembly from the radiant burner. Also, by forming the inlet assembly with a housing portion and insulation portion, the assembly can be located within the head assembly and the insulating portion prevents heat damage. 
         [0010]    In one embodiment, each identical housing aperture comprises a common fixing arrangement operable to receive any one of a plurality of different inlet assemblies, each inlet assembly having a complimentary common fixing arrangement. Accordingly, each of the inlet assemblies and the housing apertures may utilise the same complementary fixing arrangement or mechanism to enable any differently-configured inlet assembly to be received by any of the apertures. Again, this provides for enormous flexibility when reconfiguring the head assembly. 
         [0011]    In one embodiment, each identical housing aperture is distributed across a major face of the housing. Distributing the apertures across at least the major or main face of the housing maximises the available space around the inlet assemblies for coupling to fluid supplies. 
         [0012]    In an additional embodiment, the housing comprises at least one other aperture extending therethrough and the insulator comprises at least one complimentarily-located insulator aperture extending therethrough, the at least one other aperture being configured to receive at least one of an inner burner feed assembly, a pilot assembly, a thermocouple assembly and a sight glass assembly. Accordingly, the housing may also accommodate other assemblies necessary for the correct functioning of the radiant burner. 
         [0013]    In a further embodiment, the housing portion is configured to receive at least one fluid from a corresponding fluid supply and to convey at least one fluid to a corresponding outlet for supply to a combustion chamber of the radiant burner. Accordingly, there may be a one-to-one correlation between inlets for fluids received by the inlet assembly and outlets which supply those fluids to the combustion chamber. 
         [0014]    In another embodiment, the housing portion is configured to convey at least one fluid to a plurality of outlets for supply to a combustion chamber of the radiant burner. Accordingly, some inlet assemblies may provide a one-to-many relationship between inlets for fluids received by the inlet assembly and outlets which supply those fluids to the combustion chamber in order to distribute the fluid received from an inlet to many outlets within the combustion chamber. 
         [0015]    In an additional embodiment, the housing portion is configured to receive a plurality of fluids from a corresponding plurality of fluid supplies and to convey the plurality of fluids to an outlet for supply to a combustion chamber of the radiant burner. Accordingly, some inlet assemblies may provide a many-to-one relationship between fluid inlets for fluids received by the inlet assembly and outlets which supply those fluids to the combustion chamber in order to combine fluids provided by an outlet. 
         [0016]    In a further embodiment, the housing portion comprises at least one cleaning mechanism operable to clean a corresponding outlet. Cleaning the outlet(s) may be necessary in order to remove accumulated deposits. 
         [0017]    In another embodiment, the housing defines a gallery operable to distribute fluid from the inner burner feed assembly to a plenum of the radiant burner coupleable to the head assembly. Providing a gallery or plenum is a convenient arrangement to both provide fuel and oxidant to an inner burner, as well as to a plenum surrounding a foraminous burner. 
         [0018]    In yet another embodiment, the housing and the insulator together define the gallery. By shaping the housing and insulator it is possible to provide the gallery. This helps to minimise the number of parts. 
         [0019]    In a further embodiment, the housing portion is configured to extend through the gallery. Extending the housing portion through the gallery helps to ensure that no leakage from the gallery occurs. 
         [0020]    In another embodiment, each outlet extends at least partially through a corresponding outlet aperture of the insulating portion. Accordingly, the outlet may fail to extend fully through the aperture of the insulating portion, may finish flush with the aperture of the insulating portion, or may extend past the aperture of the insulating portion, depending on the conditions within the combustion chamber. 
         [0021]    In a further embodiment, the insulator portion is configured to at least partially surround the outlet. 
         [0022]    According to a second aspect, there is provided a head assembly method, comprising: providing a housing defining a plurality of identical housing apertures extending therethrough; receiving an insulator by the housing, the insulator defining a corresponding plurality of identical, complimentarily-located insulator apertures extending therethrough; and receiving at least one inlet assembly with one of the identical housing apertures, each inlet assembly comprising a housing portion configured to be received by the one of the identical housing apertures and an insulator portion configured to fill the complimentarily-located insulator aperture. 
         [0023]    In a further embodiment, the method comprises providing each identical housing aperture with a common fixing arrangement operable to receive any one of a plurality of different inlet assemblies and providing each inlet assembly with a complimentary common fixing arrangement. 
         [0024]    In another embodiment, each identical housing aperture is distributed across a major face of the housing. 
         [0025]    In yet another embodiment, the method comprises providing the housing with at least one other aperture extending therethrough and the insulator with at least one complimentarily-located insulator aperture extending therethrough and receiving at least one of an inner burner feed assembly, a pilot assembly, a thermocouple assembly and a sight glass assembly in at least one other aperture. 
         [0026]    In a further embodiment, the method comprises receiving at least one fluid from a corresponding fluid supply with the housing portion and conveying at least one fluid to a corresponding outlet for supply to a combustion chamber of the radiant burner. 
         [0027]    In another embodiment, the method comprises conveying at least one fluid to a plurality of outlets for supply to a combustion chamber of the radiant burner. 
         [0028]    In yet another embodiment, the method comprises receiving a plurality of fluids from a corresponding plurality of fluid supplies with the housing portion and conveying the a plurality of fluids to an outlet for supply to a combustion chamber the radiant burner. 
         [0029]    In a further embodiment, the method comprises providing at least one cleaning mechanism with the housing portion to clean a corresponding outlet. 
         [0030]    In another embodiment, the method comprises defining a gallery with the housing to distribute fluid from the inner burner feed assembly to a plenum of the radiant burner coupleable to the head assembly. 
         [0031]    In yet another embodiment, the housing and the insulator together define the gallery. 
         [0032]    In a further embodiment, the method comprises extending the housing portion through the gallery. 
         [0033]    In another embodiment, the method comprises extending each outlet at least partially through a corresponding outlet aperture of the insulating portion. 
         [0034]    In yet another embodiment, the method comprises at least partially surrounding the outlet with the insulator portion. 
         [0035]    According to a third aspect, there is provided an inlet assembly configured to be received by one of identical housing apertures of a housing of a head assembly for a radiant burner, the inlet assembly comprising: a housing portion configured to be received by the one of the identical housing apertures, and an insulator portion configured to fill a complimentarily-located insulator aperture of an insulator received by the housing. 
         [0036]    In one embodiment, the inlet assembly comprises a complimentary common fixing arrangement operable to be received by a common fixing arrangement of each identical housing aperture. 
         [0037]    In another embodiment, the housing portion is configured to receive at least one fluid from a corresponding fluid supply and to convey at least one fluid to a corresponding outlet for supply to a combustion chamber of the radiant burner. 
         [0038]    In a further embodiment, the housing portion is configured to convey at least one fluid to a plurality of outlets for supply to a combustion chamber of the radiant burner. 
         [0039]    In yet another embodiment, the housing portion is configured to receive a plurality of fluids from a corresponding plurality of fluid supplies and to convey the plurality of fluids to an outlet for supply to a combustion chamber of the radiant burner. 
         [0040]    In another embodiment, the housing portion comprises at least one cleaning mechanism operable to clean a corresponding outlet. 
         [0041]    In a further embodiment, the housing portion is configured to extend through a gallery defined by the housing to distribute fluid from an inner burner feed assembly to a plenum of the radiant burner coupleable to the head assembly. 
         [0042]    In yet another embodiment, each outlet extends at least partially through a corresponding outlet aperture of the insulating portion. 
         [0043]    In a further embodiment, the insulator portion is configured to at least partially surround the outlet. 
         [0044]    Other preferred and/or optional aspects of the invention are defined in the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]    In order that the present invention may be well understood, an embodiment thereof, which is given by way of example only, will now be described with reference to the accompanying drawing, in which: 
           [0046]      FIG. 1  illustrates a head assembly for a radiant burner according to one embodiment; 
           [0047]      FIGS. 2A and 2B  illustrate the head assembly of  FIG. 1  but with one inlet assembly removed; 
           [0048]      FIGS. 3A and 3B  illustrate an inlet assembly according to another embodiment; and 
           [0049]      FIGS. 4A and 4B  illustrate an inlet assembly according to a further embodiment. 
       
    
    
     DETAILED DESCRIPTION 
     Overview 
       [0050]    Before discussing the embodiments in any more detail, first an overview will be provided. A head assembly is provided which utilises a basic, preconfigured structure into which various different or identical inlet assemblies may be received. This provides for a flexible head assembly configuration which can be easily reconfigured to suit the processing or abatement of effluent gas streams from multiple different sources, and which can enable individual inlet assemblies to be removed for maintenance, when required. Providing such a modular approach gives significant operational and cost advantages. 
       Head Assembly 
       [0051]      FIG. 1  illustrates a head assembly, generally  10 , for a radiant burner according to one embodiment. Radiant burners are well known in the art, such as that described in EP 0 694 735. The head assembly comprises three main sets of components. The first is a metallic (typically steel) housing  20 , which provides the necessary mechanical strength and configuration for coupling with the remainder of the radiant burner (not shown). The second is an insulator  30  which is provided within the housing  20  and which helps to reduce heat loss from within a combustion chamber (not shown) of the radiant burner, as well as to protect the housing  20  and items coupled thereto from the heat generated within the combustion chamber. The third are inlet assemblies  50  which are received by a series of identical, standardized apertures  40  (see  FIG. 2A ) provided in the housing  20 . These inlet assemblies  50  may be provided with different configurations of inlets and outlets, or with other features, in order to suit different effluent gas abatement or processing requirements and to support the functioning of the radiant burner. However, each of the different inlet assemblies  50  is configured to fit with each of the apertures  40 . This provides the flexibility to maintain a consistent configuration into which different inlet assemblies may be fitted, as required. Also, this arrangement enables individual inlet assemblies  50  to be removed for maintenance, without needing to remove or dissemble the complete head assembly  10  from the remainder of the radiant burner. 
         [0052]    The embodiment shown in  FIG. 1  utilises six identical inlet assemblies  50 , each mounted within a corresponding one of six apertures  40 . However, it will be appreciated that any one or more of the inlet assemblies  50  may have a different configuration, provided that they can still be received within the aperture  40 . Also, it will be appreciated that not every aperture  40  may be filled with an inlet assembly  50  which receives an effluent or process fluid, or other fluid, and may instead receive a blanking inlet assembly to completely fill the aperture  40 , or may instead receive an instrumentation inlet assembly housing sensors in order to monitor the conditions within the radiant burner. Also, it will be appreciated that greater or fewer than six apertures  40  may be provided, that these need not be located circumferentially around the housing, and that they need not be located symmetrically either. 
         [0053]    As can also be seen in  FIG. 1 , additional apertures are provided in the housing  20  in order to provide for other items such as, for example, a feed  60  for an inner burner  60 A (see  FIG. 2B ), a sight glass  70  and a feed  75  for a pilot  75 A (see  FIG. 2B ). 
         [0054]      FIGS. 2A and 2B  illustrate the head assembly of  FIG. 1 , but with one of the inlet assemblies removed. 
         [0055]    As can be seen in more detail in  FIG. 2B  (which is an underside view of the head assembly), the insulator  30  is provided with apertures  40 A which align with the apertures  40 . Although in this embodiment the apertures  40 A are the same diameter as those apertures  40  extending through the housing  20 , it will be appreciated that this need not be the case and that they may be smaller. Also, although this arrangement shows the two apertures  40 ,  40 A arranged co-axially, it will be appreciated that this again need not be the case and that they may be axially offset. In such an arrangement it would be preferable for the height of a gallery (mentioned in more detail below) to be greater than the height of an insulator portion of the inlet assembly (mentioned in more detail below) or for the insulator portion to be smaller than the housing portion (mentioned in more detail below) and ‘under its shadow’ (i.e. the insulator portion extends no further radially than the housing portion). 
         [0056]    The inlet assemblies  50  are retained using suitable fixings such as, for example, bolts (not shown) which are removed in order to facilitate their removal. As can also be seen in  FIG. 2A , one internal major surface of the housing  20  is spaced away from an opposing major surface of the insulator  30  to create a gallery through which fluids may be conveyed. In this embodiment, the gallery couples with the feed  60  of the inner burner  60 A in order to convey fuel and oxidant via the apertures  80  into a plenum (not shown) surrounding a foraminous gas burner (not shown) of the radiant burner. 
       Inlet Assembly 
       [0057]    An effluent or process gas stream is provided via an inlet  100  of the inlet assembly  50  and is conveyed to each of three outlets  120 . An actuator  160  is provided which activates a cleaning mechanism to remove deposits from within the outlets  120 . The inlet assembly  50  comprises a housing portion and an insulator portion. The housing portion is generally metallic and provides the required mechanical strength for fixing the inlet assembly  50  to the housing  20  and for supporting the coupling of the necessary conduits which supply the fluid and also to support the operation of mechanisms within the inlet assembly  50 . The housing portion is generally received within the aperture  40  which falls within the housing and gallery, if present. The insulator portion is generally received within the aperture  40 A provided by the insulator  30 . The fit between the outer surface of the insulator portion and the surface of the aperture  40 A provided by the insulator  30  should be sufficiently tight to prevent heat from damaging the housing portion. If the gallery is present, the fit between the insulator portion and the aperture  40 A provided by the insulator  30  needs to be good, otherwise some of the fluid that flows through the gallery will leak directly into the combustion chamber without passing through the (outer) foraminous burner; suitable sealing means should be provided at the cold end of the insulator portion to prevent this. In one embodiment, a deformable component is provided between the housing portion and insulator portion, which is larger in diameter than the aperture  40 A and is deformably received within the aperture  40 A. The housing portion and the insulating portion are held together by fixings (not shown) located within fixing apertures (not shown), which are then sealed using a temperature resistant to sealant. 
         [0058]      FIGS. 3A and 3B  illustrate an inlet assembly  50 A according to one embodiment. As shown in  FIG. 3A , an effluent or process gas stream is provided via an inlet  100 A and is conveyed to at least one process stream outlet (not shown). Air is received via an air inlet  125  and is conveyed via an air modulating valve  130  to air outlets (not shown) which concentrically surround the process stream outlets. An actuator  160 A is provided which activates a cleaning mechanism (not shown) to remove deposits from within the outlets. The inlet assembly  50 A comprises a housing portion, generally  165 A, and an insulator portion, generally  170 A. The housing portion  165 A is generally metallic and provides the required mechanical strength for fixing the inlet assembly  50 A to the housing  20  and for supporting the coupling of the necessary conduits which supply the fluid and also to support the operation of mechanisms within the inlet assembly  50 A. The housing portion  165 A is generally received within that part of the aperture  40  which falls within the housing and gallery, if present. The insulator portion  170 A is generally received within that portion of the aperture  40 A provided by the insulator  30 . The fit between the outer surface of the insulator portion  170 A and the surface of the aperture  40 A provided by the insulator  30  should be sufficiently tight to prevent heat from damaging the housing portion  165 A. A deformable component  163 A is provided between the housing portion and insulator portion, which is larger in diameter than the aperture  40 A and is deformably received within the aperture  40 A. The housing portion  165 A and the insulating portion  170 A are held together by fixings (not shown). 
         [0059]    As can be seen in  FIG. 3B , which illustrates a section through the inlet assembly  50 A, an effluent or process gas stream is provided via the inlet  100 A and is conveyed via a chamber  110  to each of the three outlets  120 A. Air is received via the air inlet (not shown) and is conveyed via the modulating valve  130  and a chamber  140  to the three outlets  150 A which concentrically surround the outlets  120 A. The actuator  160 A activates a cleaning mechanism  170  to remove deposits from within the outlets  120 A. The inlet assembly  50 A comprises a housing portion, generally  165 A, and an insulator portion, generally  170   k  The housing portion  165 A and the insulating portion  170 A are held together by fixings (not shown) located within fixing apertures  180 , which are then sealed using a temperature-resistant sealant. 
         [0060]      FIGS. 4A and 4B  illustrate an inlet assembly  50 B according to one embodiment. As shown in  FIG. 4A , which illustrates a section through the inlet assembly  50 B, an effluent or process gas stream is provided via an inlet  100 B and is conveyed via a chamber  110 B to each of the three outlets  120 B. An actuator  160 B is provided which activates a cleaning mechanism  172  to remove deposits from within the outlets  120 B. The inlet assembly  50 B comprises a housing portion, generally  165 B, and an insulator portion, generally  170 B. The housing portion  165 B is generally metallic and provides the required mechanical strength for fixing the inlet assembly  50 B to the housing  20  and for supporting the coupling of the necessary conduits which supply the fluid and also to support the operation of mechanisms within the inlet assembly  50 B. The housing portion  165 B is generally received within that part of the aperture  40  which falls within the housing and gallery, if present. The insulator portion  170 B is generally received within that portion of the aperture  40 A provided by the insulator  30 . The fit between the outer surface of the insulator portion  170 B and the surface of the aperture  40 A provided by the insulator  30  should be sufficiently tight to prevent heat from damaging the housing portion  165 B. A deformable component  163 B is provided between the housing portion and insulator portion, which is larger in diameter than the aperture  40 A and is deformably received within the aperture  40 A. The housing portion  165 B and the insulating portion  170 B are held together by fixings (not shown) located within fixing apertures  180 B, which are then sealed using a temperature-resistant sealant. 
         [0061]    Accordingly, it can be seen that embodiments recognise that combustion of semiconductor waste gases often requires different configuration of the inlets to give optimal destruction of the gases. Ordinarily, in a system comprising at least a combustion chamber and an inlet head assembly, the configuration is fixed at the time of manufacture. Field upgrade (to accommodate process change or inaccurate specification) may well involve the complete exchange of the inlet head assembly. In extreme cases, non-standard parts may need to be manufactured. 
         [0062]    Embodiments also recognise that it would be advantageous to have available an arrangement where the function of closing off the combustion chamber (and additional support functions such as pilot, flame management) is performed by one substantial assembly. In addition, each of the process inlets would be introduced as a functionally complete sub-assembly, allowing the system to be configured and re-configured at will. 
         [0063]    Embodiments also recognise that a secondary advantage would be that for inlet maintenance procedures, only the respective inlet(s) would need to be removed, not the whole head assembly. For larger systems with heavy parts (such as systems designed for high flows seen in flat panel/solar processing and anticipated for 450 mm silicon wafer processing) this dramatically simplifies the cleaning process. 
         [0064]    The burner system comprises a combustion chamber, such as, but not limited to, for example, a foraminous burner as described in U.S. Pat. No. 5,510,093, open at both ends. The upper end is closed off by a metal flange of a head assembly according to embodiments. This has a lining of a cast ceramic fibre or other refractory material attached to it to act as a thermal insulator, protecting the metallic part(s) from thermal damage and minimising the thermal losses from the system. This flange may carry the pilot burner, thermocouple, sight glass and other features as necessary for the operation of the burner. A number of large ports are cut through the flange and the ceramic insulator so as to form passages directly into the combustion chamber. Into these ports or passages, the individual inlet assemblies are fitted. 
         [0065]    The head assembly comprises an inlet pipe, a plenum and a plurality of inlet nozzles, through which the process gases flow into the combustion chamber. The underside of the inlet plenum is fitted with a ceramic insulator in like manner to the inlet head. This insulator substantially fills the passageway in the inlet head, preventing the egress of hot gases from the combustion chamber. Elastomer seals may be fitted at the “cold” end between the flange and the plenum to make the assembly gas tight. 
         [0066]    Note that different materials may be used for the inlets and the head flange, as only the inlets are in contact with process gases. For example, the inlets may be fashioned from a stainless steel, whereas the head flange may be an aluminium alloy. 
         [0067]    The inlets may take a variety of forms for example a plurality of simple nozzles as described in U.S. Pat. No. 5,510,093, or nozzles with co-axial lances arranged for the supply of O 2 , with additional fuel pre-mixed into the process gas stream as described in EP 0802370, or nozzles with a concentric passage and a co-axial lance as described in WO 2006/013355, or simple nozzles with large concentric excess air passages for combustion of process gases with a high H 2  component. 
         [0068]    The inlet nozzles may be separate from the plenums or cast together in one piece. In one piece, the plenum and nozzles may be cast from a high temperature alloy such as ANC16 (equivalent to Inconel 600) or ANC5 (equivalent to SS310) depending on requirements. 
         [0069]    The lower end of the combustion chamber forms the outlet, through which combusted gases discharge to receive further treatment, such as air cooling, water cooling, wet scrubbing etc., as currently practised. 
         [0070]    Although embodiments relate to a burner with an annular combustion chamber, it will be appreciated that is equally applicable to other forms of combustor. 
         [0071]    It will be appreciated that separating the inlet function from the head (combustion chamber closing) function enables inlets to be separately removable. This in turn results in the option to fit any such inlet as required without the need to disturb other inlets or the head. 
         [0072]    Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.