The present invention relates generally to electronic device manufacturing abatement systems and more particularly to supplying fuel employed by the abatement systems to abate effluents.
Conventional electronic device manufacturing abatement systems abate effluents to reduce toxicity, flammability or other undesirable properties of effluents. The effluents may be produced by electronic device fabrication equipment (e.g., flat panel, semiconductor, solar, etc.). Some conventional abatement systems may abate effluents in a combustion zone that burns fuel to provide the heat necessary to abate the effluents.
A conventional abatement system may typically employ more than one nozzle for spraying fuel into the combustion zone, and often such conventional abatement systems may not have uniform combustion regions or zones. Non-uniform combustion zones may not sufficiently abate the effluent, which may result in undesirable compounds exhausting from the abatement unit.
Accordingly, methods and apparatus are desired for improving the uniformity of a combustion region or zone of an abatement system.
In one aspect, an apparatus for introducing fuel into an electronic device manufacturing effluent abatement tool is provided, including: a manifold; a fuel source adapted to supply fuel to the manifold through a fuel conduit; and a plurality of nozzles adapted to receive fuel from the manifold; wherein the manifold is adapted to supply fuel to the nozzles at a fuel velocity greater than a flame velocity.
In another aspect, a method for operating an electronic device manufacturing abatement system is provided, including: flowing fuel from a fuel supply into a manifold through a fuel conduit; and flowing the fuel from the manifold through a plurality of nozzles; wherein the manifold is adapted to flow fuel to the nozzles at a fuel velocity greater than a flame velocity.
Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings.
As discussed above, a conventional fuel burning abatement system may have several nozzles which supply fuel or a fuel/oxidant mixture to the combustion zone. For ease of description, these nozzles will be referred to herein as ‘nozzles’ or ‘fuel nozzles’, but it is understood that they may flow a fuel/oxidant mixture or fuel only. The fuel nozzles in a convention abatement system often flow fuel non-uniformly, thereby creating an uneven temperature profile in the combustion zone. For example, one nozzle may spray fuel at a higher or lower pressure than the other fuel nozzles. This difference in pressure might result in a spray pattern which differs from the spray patterns of the other nozzles. The difference in pressure might also result in an amount of fuel spraying from one nozzle which is different from the amount of fuel spraying from the other nozzles. A different spray pattern or different amounts of fuel spraying from different nozzles may result in a non-uniform temperature profile in the combustion zone.
There may be several reasons for the differences in the manner in which fuel is supplied to the several fuel nozzles in a conventional abatement unit. For example, the fuel may typically be supplied to the nozzles through supply pipes, conduits or lines. These supply lines may be of differing lengths, configurations, cross-sectional shape, internal smoothness, and may have other differences. In addition, conventional fuel burning abatement systems typically employ a flashback arrestor on each fuel line. Such flashback arrestors may prevent the fuel upstream from the flashback arrestors from igniting, by preventing a flame front from traveling back from the combustion zone through a nozzle into a fuel line or fuel source. Each flashback arrestor may be slightly different from each other flashback arrestor, and having a flashback arrestor on each fuel line may contribute to unequal fuel distribution to the combustion zone. Accordingly, for the above and additional reasons, the combustion zone in the combustion zone may not have a uniform temperature profile.
Due to such non-uniform combustion, some effluents may escape the combustion zone unabated. For example, a combustion zone temperature profile may be shaped such that a cooler zone exists on one side of the combustion zone. While chemical species in the effluent may be effectively abated in hotter portions of the combustion zone, chemical species may not be effectively abated in cooler portions of the combustion zone. Thus, in an abatement unit having nonuniform combustion, some unabated chemicals may exit the combustion zone and enter the facility exhaust.
Accordingly, there is a need for providing a more uniform temperature profile in the combustion zones of electronic device manufacturing effluent abatement systems.
The present invention provides methods and apparatus to equalize fuel flow to and fuel pressure at a plurality of fuel nozzles that spray fuel into a combustion zone of an abatement system. By equalized, we mean to reduce a difference between two fuel flow rates and/or two fuel pressures, even if by doing so the two fuel flow rates and/or two fuel pressures do not actually become equal. Accordingly, with use of the present invention, an abatement tool may exhibit a more uniform temperature profile in the combustion zone. Several aspects of the fuel flow from each nozzle may be equalized. For example, the pressure and/or flow rate of the fuel exiting each nozzle may be equalized. Additionally or alternatively, the spray profile or pattern of the fuel flow exiting each nozzle may be equalized. Still other parameters of the fuel flow exiting each nozzle may be equalized such that a more uniform combustion zone is achieved.
In order to achieve a more uniform distribution of fuel among the plurality of nozzles, the present invention provides a fuel manifold having a plurality of fuel lines which are adapted to supply fuel equally or substantially equally to each of the plurality of nozzles. Fuel lines may be equal in dimension (e.g., length, circumference, etc.), such that the fuel in each line travels an equal distance along similar channels. Alternatively, dimensions other than length may be selected for fuel lines of unequal length so that fuel which flows from the manifold arrives at the nozzles at an equalized flow rate and/or pressure. Additionally or alternatively, to further promote uniformity of fuel flow to each nozzle, the fuel may be supplied to each fuel line in the fuel manifold via a single fuel inlet. For example, a single fuel inlet may branch into two or more separate fuel lines, each fuel line being coupled to a different nozzle.
In one embodiment, the single fuel inlet may include a flashback arrestor. In such an embodiment, the flashback arrestor may be coupled to the fuel inlet, eliminating the need for a flashback arrestor on each fuel line and eliminating the variation in fuel flow that may result from the use of a different flashback arrestor on each fuel line. Accordingly, fuel may be more equally supplied into a combustion zone via the plurality of nozzles having the features of the present invention. As a result, the temperature profile in the combustion zone may be more uniform than in conventional abatement systems.
These and other aspects of the inventions are described below with reference to
Effluent to be abated may be provided to abatement system 100 from an effluent source 108. The effluent source 108 may be any type of electronic device manufacturing process unit or units (hereinafter referred to as a “process unit”) which exhausts process gases which may be abated by abatement system 100. Effluent source 108 may contain more than one processing chamber (not shown). Abatement system 100 may receive effluent from more than one effluent source 108, such as 2, 3, 4, 5, 6, or more sources. Effluent from effluent source 108 may be provided to abatement unit 101 through effluent inlet 110. More than one effluent inlet 110 may be used, and each effluent inlet may be connected to one or more effluent sources 108. Although effluent inlet 110, as shown, is adapted to introduce effluent into the combustion zone 102 through the side of the abatement unit, in another embodiment (not shown), effluent inlet 110 may introduce effluent into the combustion zone 102 by passing through fuel manifold head 112 (as described in more detail below). Fuel manifold head 112 may include fuel manifold 113, which is indicated in
Fuel may be provided to abatement unit 101 from fuel source 116, which may be a supply of hydrogen, methane or any other suitable fuel. Fuel may flow from fuel source 116 through conduit 118 into fuel inlet 119 of fuel manifold 113. In some embodiments, fuel source 116 may comprise a pump (not shown) which is adapted to pressurize the fuel. In some embodiments, a flashback arrestor 126 may be located between the fuel source 116 and the fuel inlet 119, and in these embodiments, fuel must flow through the flashback arrestor 126 prior to entering the fuel manifold 113.
Oxidant may be provided to the abatement unit 101 from oxidant source 120. Oxidant source 120 may be a supply of clean dry air, oxygen, oxygen enriched air, or any other suitable oxidant. In some embodiments oxidant from oxidant source 120 may be mixed with fuel from fuel source 116 in order to increase the temperature in the upper portions of the combustion zone. For reasons of safety, the amount of oxidant mixed with fuel outside of the abatement unit may be limited to an amount which would result in a fuel/air mixture which is sufficiently fuel rich to not be flammable without the addition of more oxygen into the abatement unit 101. In some embodiments, oxidant may enter the manifold (not shown) where it may be mixed with fuel. In some embodiments, oxidant may be provided to the abatement unit 101 through conduit 124. Oxidant supplied to abatement unit 101 through conduit 124 may be introduced into combustion zone 102, where it can mix with fuel and effluent to form a flammable mixture. In some embodiments, oxidant source 120 may comprise a pump (not shown) adapted to pressurize the oxidant.
Fuel manifold 113 may receive fuel or a fuel/air mixture, through fuel inlet 119. For ease of description, both “fuel” and “a fuel/air mixture” may be referred to hereinafter as “fuel”. The fuel received through fuel inlet 119 may be divided into a plurality of fuel lines (See
Fuel nozzles 114a-d may spray fuel into the combustion zone 102, although any suitable apparatus for providing fuel to the combustion zone 102 may be employed. The fuel nozzles 114a-d may be comprised of machined aluminum with a selectively machined output hole such that a desired spray profile is achieved. As depicted, the fuel nozzles 114a-d may be partially disposed inside the combustion zone 102. However, fuel nozzles 114a-d may be disposed entirely inside the fuel manifold head 112 with only the fuel spray output thereof exposed to an internal portion of the combustion zone 102. The manner in which the fuel nozzles 114a-d are disposed may be selected to not only effectively abate the effluent, but also to prevent fuel in the fuel manifold 113 from igniting. The fuel nozzles 114a-d receive, via the fuel manifold 113, fuel that passes through the flashback arrestor 126 which may provide additional protection against the ignition of fuel in the fuel source 116.
The plurality of fuel nozzles 114 may be adapted to spray fuel in a desired manner. For example, it may be desired that each of the plurality of fuel nozzles 114a-d spray fuel in a fan shape (e.g., triangular cross section) spray profile. In such an embodiment, the fuel sprayed from each of the plurality of fuel nozzles 114a-d may overlap before reaching the combustion zone 102. Additionally or alternatively, the plurality of fuel nozzles 114 may be adapted to form fuel sprays having a particular fuel velocity for a given fuel pressure. Such fuel velocity may be faster than a flame velocity in the combustion zone 102. Flame velocity of the combustion zone may be the rate at which flame propagates. Accordingly, the fuel may push the flame away from the plurality of fuel nozzles 114 to ensure that the ignited fuel (the flame) does not ‘flashback’ into the fuel manifold 113. Such fuel velocity may also be affected by other parameters such as fuel viscosity, pressure, etc. Such other parameters may be affected by the fuel manifold 113 as will be described in more detail below.
Flash back arrestor 126 may be any suitable flash back arrestor.
Fuel manifold 113 may be adapted to provide fuel to fuel nozzles 114a-d in selected, equal, or nearly equal, flow rates and pressures. The selected, equal, or nearly equal provision of fuel to fuel nozzles 114a-d may enable the fuel nozzles to spray fuel into the abatement unit 101, and more particularly into combustion zone 102, in selected, identical, or nearly identical spray patterns. The fuel so sprayed, may create a combustion zone with a more uniform temperature profile than may exist in a conventional abatement unit, or in a selected, non-uniform temperature profile. In some embodiments, the fuel manifold of the present invention may reduce flow differences between the fuel nozzles as compared to prior art systems. Alternatively the fuel manifold may be adapted to provide fuel to nozzles 114a-d in selected unequal flow rates and/or pressures in order to create a desired uniform or non-uniform temperature profile in the combustion zone 102.
In some embodiments, the present invention may provide more uniform fuel delivery (volume and pressure) by including a fuel line 202a-d to each fuel nozzle 114a-d and by requiring each fuel line 202a-d to be equivalent to each other fuel line 202a-d in length, cross-sectional area, and/or other parameters. It should be noted that a fuel line may include multiple segments. For example, fuel line 202a may include a primary segment 204, a secondary segment 206a, and a tertiary segment 208a. Likewise, fuel line 202b may include primary segment 204, secondary segment 206a and a tertiary segment 208b. It will be noted that more or fewer segment levels may be utilized, depending upon the number of nozzles 114 and fuel inlets 119. It should also be noted that although the fuel lines 202a-d are shown as straight lines, the fuel lines may be any suitable shape, for example, curved or circular. In some embodiments, each segment level which branches from a fuel inlet, i.e., primary segment, secondary segment, etc., may have a different cross-sectional area, as discussed in more detail below. In some embodiments, one or more segment levels may vary in cross-section over the length of the segment level.
In an alternative embodiment, the present invention may provide selected fuel delivery by including a fuel line 202a-d to each fuel nozzle 114a-d and by selecting parameters of each fuel line 202a-d, such as length, cross-sectional area, etc., such that each fuel nozzle receives a selected amount of fuel, at a selected rate and a selected pressure.
In some embodiments, fuel lines 202a-d may have smoothened or polished internal surfaces, in order to reduce differences in drag on the fuel which flows through the fuel lines.
Each of the primary fuel line segment 204, secondary fuel line segments 206a,b and tertiary fuel line segments 208a-d may be formed (e.g., machined, forged, etc.) with a geometry so as equalize the fuel flow from each of the non-combustion zone 102. For example, the width and length of each fuel nozzle 114a-d into the secondary fuel line segments 206a,b may be the same. Additionally, other geometries (e.g., corner radius, inside diameter surface roughness, etc.) may also be the same for each of the secondary fuel line segments 206a,b. Such equalization of the geometries may also be employed in the tertiary fuel line segments 208a-d. In some embodiments, a fuel manifold 113 of the present invention may have more fuel nozzles 114 than are depicted in
Fuel nozzles 114a-d are depicted in
The interior space 300 may be adapted to allow an effluent inlet 110 (not shown in
The fuel manifold head 112 may be an aluminum block with fuel lines machined into the block, although any suitable fuel manifold head 112 may be employed. The fuel manifold head 112 may be made of anodized aluminum that is manufactured (e.g., machined, forged, cast, etc.) to include fuel lines, e.g., fuel lines 204, 206 and 208. The fuel manifold head 112 may also be manufactured to include additional features such as bolts (not shown) for coupling the fuel manifold head 112 to the abatement unit 101. Other materials may be used to form the fuel manifold head 112.
In an alternative embodiment, the branching fuel lines fuel lines, which are depicted in
In operation, referring to
After passing through the flashback arrestor 126 and entering the fuel manifold 113, the fuel may be distributed equally among the fuel lines 202a-d that terminate in the fuel nozzles 114a-d. In accordance with the invention, the plurality of fuel lines 202a-d may have controlled and/or selective differences in one or more attributes such as length, cross-sectional area, angles, internal surface roughness, etc. Accordingly, the fuel may be supplied to the manifold 112 and distributed by the identical or nearly identical fuel lines 202a-d to the fuel nozzles 114a-d in identical, nearly identical or similar flow rates and/or pressures. In some embodiments, the number of fuel nozzles 114 may equal the number of fuel lines 202. Fuel may enter the combustion zone 102 via the fuel nozzles 114a-d that may be part of and/or coupled to the fuel manifold 113. Accordingly, because the fuel flow rate to, and the fuel pressure at, the fuel nozzles 114a-d may be more uniform than in conventional abatement units, the fuel spray from the plurality of fuel nozzles 114a-d may be more uniform, as well.
Additionally, the fuel manifold 113 may affect other parameters of the fuel sprayed from fuel nozzles 114a-d into combustion zone 102. For example, a fuel velocity of the fuel sprayed by fuel nozzles 114a-d may be affected desirably by the features of primary fuel line segment 204, secondary fuel line segments 206a,b and tertiary fuel line segments 208a-d. For example, a more narrow diameter in the higher order fuel line segments (i.e., closer to fuel nozzles 114) than in the lower order fuel line segments (i.e., closer to fuel inlet 119) may cause the fuel velocity to increase as the fuel flows into the higher order fuel line segments and into fuel nozzles 114. Thus, by appropriately selecting the dimensions of the primary fuel line segment 204, secondary fuel line segments 206a,b and tertiary fuel line segments 208a-d, the fuel velocity may be set higher than a flame velocity of the effluent, fuel and oxidant mixture in the combustion zone 102. When the abatement unit is operated using a fuel velocity which is higher than the flame velocity of burning fuel which has been sprayed from fuel nozzles 114, the flame front will not be able move close to the plurality of fuel nozzles 114, and flame may thus be prevented from traveling back into fuel nozzles 114.
The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For instance, the flashback arrestor 126 may not be employed if the fuel manifold 113 is designed such that the flashback arrestor 126 is not necessary. Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.
The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/029,452, filed Feb. 18, 2008, and entitled “APPARATUS AND METHODS FOR SUPPLYING FUEL EMPLOYED BY ABATEMENT SYSTEMS TO EFFECTIVELY ABATE EFFLUENTS” (Attorney Docket No. 11624/L), which is hereby incorporated herein by reference in its entirety for all purposes.
Number | Date | Country | |
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61029452 | Feb 2008 | US |