Patent ID: 12234985

DETAILED DESCRIPTION OF EMBODIMENTS

The present disclosure is directed generally to a forehearth burner assembly with nozzle-mixed oxy-fuel combustion. The burner assembly embodiments discussed herein include a gas nozzle, a fuel tube, and a fuel nozzle where the arrangement of the gas nozzle and the fuel nozzle prevent mixing of a first gas and a first fuel until the first gas and the first fuel leave the assembly. Moreover, the burner assemblies discussed herein have a wider turndown range than previous forehearth burners.

A description of example embodiments of the present disclosure follows. Although the burner assembly shown in the figures is shown in an upward orientation, the description of the assembly shown in the figures is not intended to be limited to a particular orientation.

Referring toFIG.1,FIG.1illustrates a front elevational view of burner assembly100according to the present disclosure.

The following description should be read in view ofFIGS.1and2.FIG.2illustrates burner assembly100in a cross-sectional view taken generally along line A-A inFIG.1. As shown inFIG.2, burner assembly100includes body102, gas nozzle104, fuel tube106, and fuel nozzle108. Body102includes first aperture110, second aperture112, cavity114, and gas inlet116. In one example embodiment, body102is made from stainless steel and is substantially hollow. In another example embodiment, body102is a ¾ inch stainless steel tee. In one example embodiment, body102is formed in the shape of an upside-down “T”, i.e., a T-junction where first aperture110, second aperture112, and gas inlet116form the points of the “T” shape connected by cavity114. First aperture110of body102is operatively arranged to receive gas nozzle104; second aperture112is operatively arranged to receive fuel tube106; and, gas inlet116is operatively arranged to connect with a gas source (not shown), i.e., a supply of first gas118(shown inFIG.6). First aperture110and second aperture112each have an inner circumferential surface having threads machined thereon. These threads can have various thread counts, i.e., threads per inch, and can vary from a low thread count having the advantage of being cheaper to manufacture at the cost of precision to having a high thread count having the advantage of high precision with the disadvantage of increase cost of manufacturing.

Although illustrated as an aperture centered about body102, it should be appreciated that gas inlet116can take any form sufficient to provide the appropriate volume of first gas118(shown inFIG.6) into body102and subsequently into gas nozzle104. In one an example embodiment, first gas118is oxygen or a gaseous mixture containing a substantial portion of oxygen. It should be appreciated that other gaseous mixtures could be utilized, e.g., gaseous mixtures comprising oxygen or any other gaseous oxidant that supports combustion processes.

Gas nozzle104includes first end120and second end122. First end120has an outer circumferential surface having threads machined thereon. The threads on the outer circumferential surface of first end120of gas nozzle104are arranged to engage with the threads on the inner circumferential surface of first aperture110of body102. These threads can have various thread counts, i.e., threads per inch, and can vary from a low thread count having the advantage of being cheaper to manufacture at the cost of precision to having a high thread count having the advantage of high precision with the disadvantage of increase cost of manufacturing. Second end122of gas nozzle104is arranged such that it terminates, or ends, at a first distance FD measured from first aperture110in first direction DR1with respect to body102. It should be appreciated that the threads on the outer circumferential surface of first end120of gas nozzle104are arranged such that a precise distance, i.e., first distance FD from first aperture110can be set. Additionally, gas nozzle104further includes a through-bore, i.e., first through-bore124arranged to extend along the length of gas nozzle104from first end120to second end122. First through-bore124has a first nozzle diameter ND1such that first gas118(shown inFIG.6) entering cavity114of body102via gas inlet116can flow through first through-bore124and out of second end122. The flow of first gas118(shown inFIG.6) is intended to be within the range of 0.5-10.0 ft/s.

Fuel tube106includes first end126and second end128. First end126has an outer circumferential surface having threads machined thereon. The threads on the outer circumferential surface of first end126of fuel tube106are arranged to engage with the threads on the inner circumferential surface of second aperture112of body102. These threads can have various thread counts, i.e., threads per inch, and can vary from a low thread count having the advantage of being cheaper to manufacture at the cost of precision to having a high thread count having the advantage of high precision with the disadvantage of increase cost of manufacturing. Fuel tube106further includes second through-bore130arranged within fuel tube106and between first end126and second end128of fuel tube106. Additionally, first end126of fuel tube106is arranged to be in fluid communication with a fuel source (not shown), e.g., a source of first fuel132(shown inFIG.6). First fuel132(shown inFIG.6) can be selected from: Methane, Propane, Butane, Hydrogen, Natural Gas, Carbon Monoxide, or any other gaseous fuel capable of auto-ignition at high temperatures. Second through-bore130is arranged such that first fuel132(shown inFIG.6) can flow through second through-bore130and out of second end128. Fuel tube106, when engaged with second aperture112of body102, is intended to be disposed substantially within cavity114of body102and concentric with gas nozzle104.

Second end128further includes positioning member134. Positioning member134is intended to suspend, orient, and/or center fuel tube106substantially concentric with the inner circumferential surface of first through-bore124. Positioning member134includes a plurality of support members extending radially outward from an outer circumferential surface of fuel tube106, where each of the plurality of support members contact and engage with the inner circumferential surface of first through-bore124. The plurality of support members includes first support member136, second support member138(shown inFIG.1), third support member140(shown inFIG.1), and optionally, a fourth support member142. In one example, positioning member134includes three support members, i.e., first support member136, second support member138(shown inFIG.1), and third support member140(shown inFIG.1) each extending radially from, and equally spaced about, the outer circumferential surface of fuel tube106, i.e., substantially spaced apart 120 degrees from each other about the outer circumferential surface of fuel tube106. In one example, positioning member134includes four support members, i.e., first support member136, second support member138(shown inFIG.1), third support member140(shown inFIG.1), and fourth support member142each extending radially from, and equally spaced about, the outer circumferential surface of fuel tube106, i.e., substantially spaced apart 90 degrees from each other about the outer circumferential surface of fuel tube106. It should be appreciated that any configuration of radially extending support members sufficient to suspend fuel tube106substantially concentric with first through-bore124is contemplated herein.

Additionally, the second end128of fuel tube106has an aperture arranged to receive fuel nozzle body146of fuel nozzle108, i.e., third aperture144. Third aperture144has an inner circumferential surface arranged to engage with first end148of fuel nozzle body146as discussed below. The inner circumferential surface of third aperture144has machined threads arranged thereon. Again, these threads can have various thread counts, i.e., threads per inch, and can vary from a low thread count having the advantage of being cheaper to manufacture at the cost of precision to having a high thread count having the advantage of high precision with the disadvantage of increase cost of manufacturing. It should be appreciated that this threaded connection will allow for ease of replacement of fuel nozzle108in the event that it is damaged or a particular application requires a different nozzle diameter or length.

The following should be read in view ofFIGS.2and3A-3C. Fuel nozzle108has a fuel nozzle body146(shown inFIG.3A). Fuel nozzle body146(shown inFIG.3A) has first end148and second end150. First end148of fuel nozzle body146is arranged to engage with and be removably secured to third aperture144of second end128of fuel tube106. Fuel nozzle body146further includes third through-bore152which is substantially concentric with second through-bore130of fuel tube106. As will be discussed below, third through-bore152terminates at second end150of fuel nozzle body146and has a second nozzle diameter ND2. Second nozzle diameter ND2is selected such that first fuel132(shown inFIG.6) can flow through second through-bore130and third through-bore152and out of second end150of fuel nozzle body146. The flow rate of first fuel132(shown inFIG.6) is intended to be within the range of 30.0-330.0 ft/s.

When first end148of fuel nozzle body146is engaged with third aperture144of fuel tube106, and first end126of fuel tube106is engaged with second aperture112of body102, second end150of fuel nozzle body146is arranged to terminate, or end, a second distance SD from first aperture110. In one example embodiment, first distance FD is less than second distance SD. In other words, second end150of fuel nozzle body146extends past second end122of gas nozzle104. In one example, second distance SD is between 0.0-1.0 inches greater than first distance FD. This arrangement prevents mixing and ignition of first gas118(shown inFIG.6) and first fuel132(shown inFIG.6) until both first gas118(shown inFIG.6) and first fuel132(shown inFIG.6) are outside of the burner assembly, i.e., proximate mixing area174(shown inFIG.6). It should be appreciated that, in a preferred embodiment, gas nozzle104and fuel nozzle108are made from stainless steel or bored from solid stock stainless steel and machined. Previous forehearth burners utilize Inconel material for its ability to withstand higher operating temperatures; however, with the benefits of the present burner assembly, the nozzle can be made from stainless steel as the combustion takes place substantially, or completely, outside of the gas nozzle104. In one example embodiment, gas nozzle104is made from303or304grade stainless steel and fuel nozzle is made from310grade stainless steel. Thus, one potential advantage over previous assemblies is that, as steel is cheaper to obtain and machine, the assembly discussed in the present disclosure is cheaper to manufacture than previous versions using Inconel.

FIGS.3A-3Cillustrate a side elevational view, a cross-sectional side elevational view, and a front view of fuel nozzle108, respectively, according to the present disclosure.FIG.3Cis taken from the perspective of second end150of fuel nozzle body146. As can be seen inFIGS.3A-3C, in one example of fuel nozzle108, fuel nozzle body146includes at least first body portion154and second body portion156. First body portion154is arranged proximate first end148of fuel nozzle body146and has a first outer diameter OD1. Second body portion156is arranged proximate second end150of fuel nozzle body146and has a second outer diameter OD2. Between first body portion154and second body portion156there is a first outer transition surface164which transitions the outer surface of fuel nozzle body146from first outer diameter OD1to second outer diameter OD2.

Third through-bore152of fuel nozzle body146further includes a first portion160and a second portion162. First portion160of third through-bore152is arranged proximate first end148of fuel nozzle body146, and second portion162of third through-bore152is arranged proximate second end150of fuel nozzle body146. First portion160of third through-bore152has a first inner diameter ID1(not shown) and second portion162of third through-bore152has a second inner diameter ID2(not shown). Between first portion160and second portion162of third through-bore152there is a first inner transition surface168which transitions the inner surface of third through-bore152from first inner diameter ID1(not shown) to second inner diameter ID2(not shown).

FIG.4illustrates an example embodiment of burner assembly100according to the present disclosure. The embodiment illustrated inFIG.4is substantially similar to the embodiment illustrated inFIG.2, with a few alterations. For example,FIG.4illustrates that first end120of gas nozzle104can further include a stop170arranged to prevent further rotational engagement of the threads previously described within the inner circumferential surface of first aperture110. Similarly, first end126of fuel tube106also has a stop170arranged to prevent further rotational engagement of the threads previously described on the inner circumferential surface of second aperture112. Stop(s)170create a precise stopping point for both gas nozzle104and fuel tube106such that the first distance FD and second distance SD can be set with high precision. Additionally, although not illustrated, it should be appreciated that the connection between gas nozzle104and first aperture110, and the connection between fuel tube106and second aperture112can be threaded. Moreover,FIG.4also illustrates that gas nozzle104and fuel nozzle108can co-terminate an equal distance from first aperture110of body102, i.e., first distance FD and second distance SD are substantially equal. This arrangement also allows for external mixing of first gas118and first fuel132outside of gas nozzle104.

FIGS.5A-5Cillustrate an example embodiment of fuel nozzle108having fuel nozzle body146. As shown inFIGS.5A-5C, fuel nozzle body146can include first body portion154, second body portion156, and third body portion158. First body portion154is arranged proximate first end148of fuel nozzle body146and has a first outer diameter OD1. Second body portion156is arranged proximate second end150of fuel nozzle body146and has a second outer diameter OD2. Third body portion158is arranged between first body portion154and second body portion156and has a third outer diameter OD3, where OD3is less than OD1and greater than OD2. Between first body portion154and third body portion158there is a first outer transition surface164which transitions the outer surface of fuel nozzle body146from first outer diameter OD1to third outer diameter OD3. Between third body portion158and second body portion156there is a second outer transition surface166which transitions the outer surface of fuel nozzle body146from third outer diameter OD3to second outer diameter OD2.

Additionally, third through-bore152of fuel nozzle body146further includes a first portion160and a second portion162. First portion160of third through-bore152is arranged proximate first end148of fuel nozzle body146, and second portion162of third through-bore152is arranged proximate second end150of fuel nozzle body146. First portion160of third through-bore152has a first inner diameter ID1(not shown) and second portion162of third through-bore152has a second inner diameter ID2(not shown). Between first portion160and second portion162of third through-bore152there is a first inner transition surface168which transitions the inner surface of third through-bore152from first inner diameter ID1(not shown) to second inner diameter ID2(not shown).

FIG.6illustrates a partial cross-sectional view of burner assembly100illustrated inFIG.4during operation. The following example description should be read in view ofFIGS.1-6. During operation, a first gas source connected to gas inlet116provides first gas118which flows through gas inlet116into cavity114of body102of burner assembly100. Cavity114is sufficiently voluminous to accept first gas118and redirect it through first aperture110, around the volume taken up by fuel tube106and fuel nozzle108, into first end120of gas nozzle104, along first through-bore124of gas nozzle104, and out of second end122of gas nozzle104. Simultaneously, a fuel source (not shown) connected to fuel tube106provides first fuel132which flows from first end126of fuel tube106, through second through-bore130, to second end128of fuel tube106, into third through-bore152of fuel nozzle108and out into mixing area174. Once first gas118and first fuel132mix, the temperature experienced in mixing area174is sufficient for auto-ignition of the gas-fuel mixture, which creates the combustion176for the burner assembly. Importantly, due to the position of the external mixing area174, several advantages are realized. First, as the gas does not mix within gas nozzle104, this arrangement experiences less misfires/backfires. Additionally, as combustion is taking place outside of the burner assembly, the entire assembly, including the gas nozzle104, experiences reduced operating temperatures and decreasing overall failure rate of the assembly. It should be appreciated that, although not shown, an ignitor can be provided such that combustion176does not rely on auto-ignition as described herein.

As discussed above, the flow rate of first gas118is intended to range from 0.5-10.0 ft/s. The flow rate of first fuel132is intended to range from 17.5-450.0 ft/s. Thus there is a ratio of between 1:35-1:45 in the flow rate of the first gas118and the flow rate of the first fuel132. This difference in flow rate allows for the wider/broader turndown ratio during operation, e.g., 10:1 as opposed to previous burners where the ratio is closer to 3:1 or 4:1. This difference in flow rate is a result of the difference in diameters at the end of gas nozzle104and the end of the fuel nozzle108. The flow rate of first fuel132is dependent on the diameter of the second end150of fuel nozzle body146. The flow rate of first gas118is dependent on the diameter of the second end122of gas nozzle104subtracted by the diameter of the second end150of fuel nozzle body146.

While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.