Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
  • F23R3/16—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration with devices inside the flame tube or the combustion chamber to influence the air or gas flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/005—Combined with pressure or heat exchangers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
  • F23R3/04—Air inlet arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
  • F23R3/283—Attaching or cooling of fuel injecting means including supports for fuel injectors, stems, or lances
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
  • F23R3/286—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply having fuel-air premixing devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
  • F23R2900/03041—Effusion cooled combustion chamber walls or domes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
  • F23R2900/03042—Film cooled combustion chamber walls or domes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
  • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
  • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
  • F23R3/04—Air inlet arrangements
  • F23R3/10—Air inlet arrangements for primary air
  • F23R3/12—Air inlet arrangements for primary air inducing a vortex

Definitions

• the invention is related to an optimized cooling arrangement for a base plate configured to preferentially deliver cooling fluid to regions susceptible to flashback and flame holding in a can-annular combustor that utilizes alternating swirl mains, where the optimized cooling arrangement reduces NOx and CO emissions.
• the main burners may be held in place around the pilot burner and extend through a base plate that is oriented transverse to the main burners. Similar to the pilot burner, each main burner receives a respective portion of the flow of compressed air received from a compressor. Each flow of compressed air flows through its respective main burner where it is mixed with fuel to form a main burner air and fuel mixture.
• the main burner mixture may be swirled by flow control surfaces in the main burners that impart circumferential motion to the axially moving main burner mixture. This swirled mixture continues downstream until the main burner flows and the pilot burner flow blend at which point the main burner flows are ignited by the pilot flame.
• the main burner mixture is usually leaner than the pilot burner mixture and hence stable combustion relies on the anchoring effect of the pilot burner mixture.
• FIG. 1 shows a prior art combustor arrangement of a can-annular gas turbine engine.
• FIG. 3 shows the base plate and prior art cooling apertures of FIG. 2 and swirl of an alternative prior art swirler arrangement.
• FIG. 4 shows an end view of a combustor arrangement utilizing the base plate, the prior art cooling apertures, and alternative prior art swirler arrangement of FIG. 3.
• FIG. 5 shows a base plate and alternating swirl mains with a cooling
• FIG. 6 shows an end view of a combustor arrangement and an alternate exemplary embodiment of the cooling arrangement disclosed herein.
• the present inventors have recognized that combustion arrangements using premix main burners surrounding a pilot burner may develop zones of varying fuel richness within the combustor when the swirlers in the main burners impart alternating swirls to the main burner flows.
• the inventors have determined that in zones where adjacent portions of adjacent main burner flows flow inbound (into the pilot flame), a fuel-rich zone may be formed. The high fuel content in these inbound zones increases a propensity for flashback and flame holding.
• the inventors have
• a fuel-lean zone may be formed.
• the inventors have further determined that cooling fluid flowing through the base plate is entrained in the main burner flows.
• the inventors have exploited this knowledge and have devised a unique apparatus configured to reduce the opportunity for flashback and flame holding in such alternating swirl arrangements.
• the improved combustor apparatus described herein preferentially delivers increased cooling air flow to fuel-rich inbound zones to decrease the fuel to air mixture level in those zones. Reducing the amount of fuel in these inbound zones reduces the ability of the flame to flashback through these zones and to hold where not desired.
• the improved combustor apparatus may preferentially deliver reduced cooling air flow to the fuel-lean outbound zones. This associated reduction in cooling flow helps offset the increased flow of coolant to the inbound zones, and thus instead of increasing a total coolant flow through the combustor, the overall rate of cooling flow through the combustor is essentially maintained. Maintaining the same or similar overall total cooling flow helps to maintain engine efficiency and to reduce NOx and CO emissions that may otherwise be associated with an increase in total cooling air flow.
• FIG. 1 shows a combustor arrangement 10 of a prior art can annular gas turbine engine.
• Compressed air 12 received from a compressor flows generally from an upstream end 14 of the combustor arrangement 10 toward a downstream end 18 along a combustor arrangement longitudinal axis 18.
• a plurality of premix main burners 20 is disposed circumferentially about a pilot burner 22 and concentric to the combustor arrangement longitudinal axis 18.
• Each main burner 20 receives a portion of the compressed air 12, the portion thereby becoming a respective main burner flow 24 through each main burner 20.
• the pilot burner receives a portion of the compressed air 12 that becomes the pilot flow (not shown).
• each main burner 20 Within each main burner 20 is a swirler assembly 28 (not visible) and fuel injectors (not shown) that introduce fuel into the compressed air to create a main burner fuel and air mixture.
• Each swirler assembly 26 imparts circumferential movement to a respective main burner flow 24.
• each main burner flow 24 exhausting from a main burner outlet 28 is moving both axially and circumferentia!ly to form a helical flow (not shown).
• the main burner outlet 28 may be disposed at an end of an optional main burner aft extension 30 as shown, or slightly more upstream when the optional main burner aft extension 30 is not present.
• a base plate 40 is oriented transverse to the combustor arrangement longitudinal axis 18 and to the longitudinal axes 42 of each main burner 20 and helps to support each main burner 20.
• the base plate 40 includes main burner apertures 44 through which the main burners 20 extend.
• the base plate 40 separates the combustor arrangement 10, thereby forming an upstream region 46 and a downstream region 48 in which combustion occurs.
• Cooling apertures 50 of uniform size and a symmetric pattern are disposed about and through the base plate 40 to allow compressed air 12 to act as a cooling fluid 52 and flow through the base plate 40 to provide necessary cooling in a prior art cooling arrangement.
• the pilot burner 22 likewise may include a pilot swirler (not shown) proximate the base plate 40 that imparts a swirl to the pilot flow, and fuel injectors that introduce fuel into the compressed air to create a pilot flow air-fuel mixture.
• the swirled pilot flow is bounded by a pilot burner cone arrangement 60 that may include an inner pilot cone 62 and an outer pilot cone 84 that surrounds the inner pilot cone 62 and defines an annular gap 66 there between.
• Compressed air 12 may flow in the annular gap 86 and exhaust an annular gap outlet 68.
• the annular gap outlet 88 may occur upstream of or flush with a pilot cone arrangement downstream end 70.
• the pilot burner flow anchors combustion via a pilot flame that exists in a pilot flame zone 74 proximate the pilot cone arrangement downstream end 70.
• Each main burner swirled flow travels from the respective main burner outlet 28 until it reaches the pilot flame zone 74 where it is ignited by the pilot flame.
• the swirled pilot flow and the swirled main burner flows form a combustion flame in a combustion flame zone 76 which is similar to the pilot flame zone 74, though larger.
• the swirled main flows are bounded on a radially outward side 78 by a combustor liner 80.
• On a radially inward side 82 the swirled main flows are bounded by the outer pilot cone 84. This radially asymmetric bounding causes radially asymmetric aerodynamics discussed further below.
• F!G. 2 shows the base plate 40 and associated cooling arrangement of FIG. 1 removed from the combustor arrangement 10 and looking from the downstream end 16 toward the upstream end 14 along the combustor arrangement longitudinal axis 18.
• the swirler assemblies (not visible) impart swirl to each main burner flow 24 in a same direction 102 which is, in this view, counter-clockwise, thereby forming swirled main flows 104.
• adjacent portions 108 of adjacent swirled main flows 108 travel axially along the combustor arrangement longitudinal axis 18, they eventually meet while traveling in opposite linear directions.
• a clockwise swirled main flow 130 is traveling in an linear outbound direction 1 12 away from the combustor arrangement longitudinal axis 18 and the pilot burner 22 centered there about and an adjacent, second swirled flow 132 is traveling in a linear inbound direction 1 16 toward the pilot burner 22.
• the clashing of opposite flow directions causes shear and vortices and these causes combustion instabilities and increased pulsations and increased NOx and CO emissions etc.
• an outbound-zone is created between the counter-clockwise swirled main flow 132 and the clockwise swirled main flow 130 when the counter-clockwise swirled main flow 132 is disposed adjacent to and circumferentially to the left of the clockwise swirled main flow 130.
• the inbound portions of the flows encounter the swirled pilot flow and the swirled pilot flow acts against extensive inbound penetration.
• the premixed inbound portions mix with a perimeter of the premix pilot flow and flow axially along with the premix pilot flow.
• the outbound portions of the main flows will also be guided radially outward by the diverging inner pilot cone 62, enhancing the outbound effect in the outbound-zone 138.
• the pilot flame is receiving an influx of a fuel and air mixture that contributes to the combustion flame.
• the pilot flame is not receiving an influx of fuel and air mixture, but instead fuel and air in the outbound-zones is being directed away from the pilot flame.
• the fuel from the inbound zones mixing with the perimeter of the pilot flame creates conditions that tend to allow flashback and flame holding of the combustion flame. During these conditions the flame may sit on the pilot cone and/or on the swir!ers resulting in hardware damage.
• One factor that may contribute to the tendency of the flame to sit on the pilot cone may be the annular gap outlet 88 from which relatively slow-moving cooling fluid exhausts.
• the relatively slow-moving cooling fluid from the annular gap 66 mixes with the fuel and air mixture in the inbound-zone, and this slows the overall velocity of the merged cooling air and fuel and air mixture, which makes it easier for the flame to sit.
• cooling fluid 52 flowing through the cooling apertures 50 of the base plate 40 becomes entrained in the main swirled flows 104. It was noted in particular that certain portions of the cooling fluid 52 flowing through the cooling apertures 50 becomes entrained in a manner that directs the entrained flow into the inbound-zone. From this, the inventors concluded that the uniform cooling hole pattern of the prior art shown in FIG. 4 could be improved by tailoring a new pattern for the cooling apertures 50.
• the new pattern could preferentially deliver cooling fluid 52 to portions of the combustion arrangement more prone to flashback and flame holding due to an abundance of available fuel and/or a relatively slow flow rate, such as the inbound-zones 134.
• the inventors further realized that other portions of the pattern that are not delivering cooling fluid 52 to the inbound- zones 134 could be adjusted to permit less cooling flow there through.
• This reduction in cooling flow could be used to offset the increase in cooling flow used to direct cooling fluid 52 to the inbound-zones 134.
• the offset permits a total flow of cooling fluid 52 through the combustor arrangement 10 to remain the same or close to the same.
• Maintaining the same or similar total cooling flow prevents a reduction in engine operation efficiency associated with an increase in cooling air flow and prevents the formation of additional NOx and CO emissions often associated with an increase in cooling flow.
• FIG. 5 shows an exemplary embodiment of a new base plate cooling
• the base plate 40 is divided into even arc-sectors 180 delimited by planes 162 in which reside the combustor arrangement longitudinal axis 18 and main burner longitudinal axes 164, (which are parallel to the combustor
• the planes 162 extend radially from the combustor arrangement longitudinal axis 18 and bisect a main burner 20 on opposite sides of the combustor arrangement longitudinal axis 18. In this view, there are four planes 162, each bisecting two main swirlers 20.
• the high-flow region 156 of the base plate 40 is an arc-sector 160 that includes the high-flow cooling apertures 152.
• the low-flow region 158 of the base plate 40 is an arc-sector 160 that includes the low-flow cooling apertures 154.
• the high-flow region 156 is upstream of and circumferentially aligned with a modified inbound-zone 134'
• the low-flow region 158 is upstream and circumferentially aligned with a modified outbound-zone 136'.
• the modification includes a relatively leaner mixture.
• the modification includes a relatively richer mixture.
• a majority of the high-flow cooling apertures 152 are disposed radially outward of the main burner longitudinal axes 164 because this location facilitates the cooling fluid 52 being entrained and delivered to the inbound- zone as desired. This configuration has been demonstrated and has proven to reduce the likelihood of flashback and flame holding.
• a relatively high flow rate in the high-flow region 156 can be achieved by various ways other then by changing a diameter of the cooling apertures.
• smaller or fewer apertures or both may be used, in addition, other configurations of high flow regions and low flow regions effective to mitigate flashback and flame holding can be envisioned and are within the scope of this disclosure.
• the regions shown are arc-sectors having an arc-length of 1/8 of the total arc-length, they could take any shape, such as shorter or longer arc-lengths.
• a high or low-flow region could be a circular, square, or other shape within the bounds of the base plate 40.
• the shape of the region could be formed to match a shape of the inbound-zone being targeted. For example, if the inbound-zone being targeted were characterized by a spherical shape, the high-flow region could be circular. Likewise, if the inbound-zone being targeted were
• the high-flow region could match that shape in whatever size necessary to accommodate any flow convergence and/or divergence of the cooling fluid flowing through the high-flow region as it travels toward the inbound- zone.
• a shape of a cross section of the cooling fluid flowing through the high-flow region would match a shape and/or size of a cross section of the inbound- zone when the cooling fluid reaches the inbound-zone, and a maximum amount of the inbound-zone would be infiltrated with the cooling fluid.
• the shaping of the high-flow region could be done in any number of ways, including simply placing several same or similar sized and/or shaped cooling apertures in the proper place in the proper shape. Alternately, individual cooling apertures of varying sizes and shapes could be
• the pilot cone may be configured to bias the flow of cooling fluid.
• a shape of the annular gap 66 may be varied to preferentially deliver more cooling fluid from the annular gap 66 to the inbound-zone 134 and less cooling fluid from the annular gap 68 to the outbound zone 138. This may be accomplished in an exemplary embodiment by varying a shape of the outer pilot cone 64 such that it appears to undulate csrcumferentially. This can produce an annular gap 68 where a width 170 of the gap varies circumferentially with the undulations.
• the width 170 can be such that a relatively larger width 172 is present proximate the inbound zone 134 to allow more annular gap cooling fluid to flow into the inbound zone 134, The relatively smaller width 174 is present proximate the outbound zone 136 to allow less annular gap cooling fluid to flow into the outbound zone 138.
• the inner pilot cone 62 may be similarly undulated.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)

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• 2013
  • 2013-12-26 US US14/140,599 patent/US9939156B2/en active Active
• 2014
  • 2014-05-23 EP EP14734317.2A patent/EP3004742B1/en active Active
  • 2014-05-23 JP JP2016518338A patent/JP6419166B2/ja active Active
  • 2014-05-23 WO PCT/US2014/039260 patent/WO2014197219A1/en not_active Ceased
  • 2014-05-23 CN CN201480031706.2A patent/CN105264294B/zh active Active

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