EP0062149B1 - Catalytic combustor having secondary fuel injection for a stationary gas turbine - Google Patents

Catalytic combustor having secondary fuel injection for a stationary gas turbine Download PDF

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Publication number
EP0062149B1
EP0062149B1 EP82101111A EP82101111A EP0062149B1 EP 0062149 B1 EP0062149 B1 EP 0062149B1 EP 82101111 A EP82101111 A EP 82101111A EP 82101111 A EP82101111 A EP 82101111A EP 0062149 B1 EP0062149 B1 EP 0062149B1
Authority
EP
European Patent Office
Prior art keywords
fuel
primary
combustion
zone
catalytic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82101111A
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German (de)
English (en)
French (fr)
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EP0062149A1 (en
Inventor
Paul Walter Pillsbury
Serafino Mario Decorso
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Electric Corp
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Westinghouse Electric Corp
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Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Publication of EP0062149A1 publication Critical patent/EP0062149A1/en
Application granted granted Critical
Publication of EP0062149B1 publication Critical patent/EP0062149B1/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C13/00—Apparatus in which combustion takes place in the presence of catalytic material
    • 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
    • F23R3/34—Feeding into different combustion zones
    • F23R3/346—Feeding into different combustion zones for staged combustion
    • 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
    • F23R3/40—Continuous combustion chambers using liquid or gaseous fuel characterised by the use of catalytic means

Definitions

  • This invention relates to stationary combustion turbines and more particularly to the implementation of catalytic combustion in such turbines to characterize the turbine operation with low NO x emissions.
  • compressor discharge air is supplied at an elevated temperature to support the combustion of fuel supplied through one or more nozzles at the upstream end of multiple combustor baskets.
  • Combustion products are directed through ducting to the turbine blades.
  • the temperature of the compressor discharge air used in the fuel-air mix depends on the compression ratio of the compressor which is based on overall turbine design considerations. For any particular compressor design, the compressor discharge temperature also depends on the operating point of the turbine during the startup and load operating modes. Generally, as turbine speed or load increases, the compressor discharge air temperature increases.
  • the invention resides in a catalytic combustion system for a stationary gas turbine comprising a combuster basket having a tubular sidewall defining a primary combustion zone therein, a primary nozzle capable of supplying fuel for combustion in the primary zone, said combustor basket sidewall also defining a secondary zone downstream of the primary zone and including a downstream diffuser end portion which defines an expanding path over at least part of the secondary zone, the system further comprising secondary injection nozzles located outside of said basket and capable of injecting fuel into the secondary zone for mixing with the primary combustion product flow to provide a fuel-air mixture at the combustor basket outlet sufficiently mixed and heated to undergo catalytic reaction, and a catalytic unit being provided capable of receiving the outlet flow from said combustor basket, characterized by means for selectively supplying fuel to said primary nozzle and to said secondary injection nozzles so that secondary fuel is supplied to energize the turbine when conditions for catalytic reaction are achieved, and so that primary fuel is supplied to energize the turbine when no secondary fuel is being supplied, and to
  • Figure 1 a generalized schematic representation of the catalytic combustion system according to the preferred embodiment of the invention.
  • Aturbine or generally cylindrical catalytic combustor 10 is combined with a plurality of like combustors (not shown) to supply hot motive gas to the inlet of the turbine (not shown in Figure 1) as indicated by the reference character 12.
  • the combustor 10 includes a conventional monolithic catalytic structure having substantial distributed catalytic surface area which effectively supports catalytic combustion (oxidation) of a fuel-air mixture flowing through the unit 14.
  • the catalytic structure is a honeycomb structure having its passages extending in the gas flow direction.
  • the combustor 10 includes a zone 11 into which fuel, such as oil, is injected by nozzle means 16 from a fuel valve 17 where fuel-air mixing occurs in preparation for entry into the catalytic unit 14. Proper mixing preferably entails vaporization of 80% to 90% of the injected fuel for efficient and effective catalytic reaction.
  • the fuel-air mix temperature (for example 427°C) required for catalytic reaction is higher than the temperature (for example 371°C) of the compressor discharge air supplied to the combustors from the enclosed space outside the combustor shells.
  • the deficiency in air supply temperature in typical cases is highest during startup and lower load operation.
  • a primary combustion zone 18 is accordingly provided upstream from the fuel preparation zone 11 within the combustor 10.
  • Nozzle means 10 are provided for injecting fuel from a primary fuel valve 22 into the primary combustion zone 18 where conventional flame combustion is supported by primary air entering the zone 18 from the space within the turbine casing through openings in the combustor wall.
  • a hot gas flow is supplied to the catalytic fuel preparation zone where it can be mixed with the fuel and air mixture in the fuel preparation zone 11 to provide a heated fuel mixture at a sufficiently high temperature to enable proper catalytic unit operation.
  • the fuel injected by the nozzle means 16 for combustion in the catalytic unit is a secondary fuel flow which is mixed with secondary air and the primary combustion products which supply the preheating needed to raise the temperature of the mixture to the level needed for entry to the catalytic unit.
  • the catalytic combustion system is operated by a generally conventional analog or digital computer or digital/analog speed and load control 24 which operates the primary and secondary fuel valves 22 and 17 through conventional electropneumatic valve controls 26 and 28 respectively.
  • the control 24 is preferably arranged to operate the primary fuel system to energize the turbine through primary combustion only during startup and, after synchronization, during loading up to a predetermined load level. Thereafter, primary combustion is reduced by primary fuel cutback as secondary fuel flow is initiated by the control 24 to provide for turbine energization primarily through catalytic combustion.
  • primary combustion provides the turbine energization needed to drive the turbine operation to the point where motive gas temperatures are sufficient for sustained catalytic combustion operation.
  • FIGs 2 and 3 there is shown a structurally detailed catalytic combustion system 30 embodying the principles described for the combustor 10 of Figure 1.
  • the combustion system 30 generates hot combustion products which pass through stator vanes 31 to drive turbine blades (not shown).
  • a plurality of the combustion systems 30 are disposed about the rotor axis within a turbine casing 32 to supply the total hot gas flow needed to drive the turbine.
  • the catalytic combustor 30 includes a combustor basket 40, a catalytic unit 36 and a transition duct 38 which directs the hot gas to the annular space through which it passes to be directed against the turbine blades.
  • the combustor basket 40 is mounted on the casing 32 by bolt means 42 and preferably is provided with a primary and plural (six) secondary sidewall fuel nozzles 44 and 46. Fuel supplied through the primary nozzle 44 (readily removable for maintenance) is mixed with primary combustion support air, which enters the basket 40 through sidewall scoops 48 (or openings), and burned in a primary combustion zone 50 to provide hot gas for driving the turbine or preheating a downstream fuel-air mixture to the level required for catalytic reaction. Primary combustion support air also enters the basket 40 in this case through swirlers 52 which are disposed coaxially about the primary nozzle 44. Dilution air enters the zone 50 primarily through scoops 49.
  • the length of the primary zone 50 accordingly is sufficient to provide the space needed for primary combustion to occur followed by the space needed for mixing of the primary combustion products with dilution air.
  • the primary zone sidewall is conventionally structured from a plurality of sidewall rings which are securely held together in a telescopic arrangement by corrugated spacer bands.
  • the spacer bands thus provide an annular slot between adjacent sidewall ring members through which air is admitted to cool the internal sidewall ring surfaces.
  • the cross-section of the primary zone increases slightly in the downstream direction.
  • Primary ignition is provided by a conventional spark igniter in a tube 35 in one or more of the combustors 40.
  • Cross flame tube connectors indicated by reference character 37 are employed to ignite the other combustors 40.
  • the supplemental use of a conventional burner to produce part of the total fuel combustion in the system 30 enables compensation to be made for dropoff in catalytic activity with turbine operation time.
  • the ratio of conventional combustion to catalytic combustion is sufficient under all higher output operating conditions to achieve the needed combustion assistance without the production of an unacceptable NO x penalty.
  • the resultant mix expands as it passes through an outwardly flared diffuser 56 which forms an end portion of the basket 40. It then enters a catalytic reaction element 27 in the catalytic unit 36.
  • Proper penetration of secondary air jets into the combustor is important from the standpoint of fuel/air mixing because the jets carry the secondary fuel with them. If penetration is excessive, the center of the catalyst element receives too much fuel; if too little penetration is obtained, the edges of the catalyst receive too much fuel. For optimum mixing, the maximum penetration should be 33% of the tubular combustor diameter.
  • the diffuser 56 is employed because a smaller path diameter is needed for satisfactory fuel mixing in the combustor basket 40 as compared to the path diameter needed for catalytic combustion.
  • injection of secondary fuel into a smaller diameter basket provides improved fuel/air mixing and better fuel/air uniformity across the face of the catalyst.
  • the use of a larger basket diameter enables use of a larger catalyst diameter which results in a lower catalyst inlet velocity and procedures a lower pressure drop and improved combustion efficiency.
  • the flared shape of the diffuser 56 is preferably formed to prevent hot gas flow separation (i.e. to preventturbulent layer formation near the diffuser wall). Back pressure from the catalyst structure provides forces needed to expand gas streamlines out to the diffuser wall and prevent turbulent layer buildup.
  • the system operates so that the residence time for the gaseous mixture (in this case, preheated to 427°C) in the secondary fuel preparation zone 54 is less than the ignition delay time from the primary zone 50. In this way, flame is contained in the primary combustion zone 50 away from the catalytic element 36.
  • the secondary fuel injection plane 58 is spaced from the catalyst face by a distance which is sufficient to permit proper fuel mixing (substantial uniformity across the catalyst face) and preparation for the catalyst but which is less than the critical distance which allows the fuel-air mixture to auto-ignite before it crosses the secondary zone 54 into the catalytic element. Normally, the fuel-air mixture is driven across the zone 54 within several milliseconds to avoid auto-ignition.
  • the secondary fuel nozzles 46 are supported preferably with a predetermined spacing outwardly from the combustor sidewall. In this case, the nozzles are angled for transversely directed fuel injection with a predetermined angle of spread.
  • the cooling air also atomizes the fuel to a fuel fog as it is injected through the scoops 55 into the combustor fuel preparation zone 54.
  • An additional air jet joins the nozzle flow in the scoop 55 and provides any additional air needed to achieve the desired fuel-air ratio (preferably lean) in the fuel preparation zone 56.
  • the scoop size and nozzle placement both can be varied to modify the amount of such air jet flow.
  • the diameter of the catalytic element is determined mainly by the maximum allowable reference gas velocity for complete emissions burnout at an acceptable pressure loss. Higher gas velocities require longer catalyst beds and result in higher emissions.
  • the mass transfer units required for complete emissions burnout are inversely proportional to the square root of reference velocity in laminar flow, but the effect of reference velocity on the mass transfer rate decreases with an increase in channel Reynolds number.
  • the maximum allowable reference velocity is limited in turbulent flow by the restriction of pressure losses.
  • the low limit boundary of reference velocity for the region of operability may be determined by flashback considerations in the fuel preparation zone.
  • the catalytic element includes a can 30 within which a catalytic honeycomb structure is conventionally supported by suitable means.
  • the catalyst characteristics can be as follows:
  • Figure 4 shows a modification of the combustor basket 40 shown in Figures 2 and 3.
  • the combustor basket 40 is pinched-in to a diameter of, for example 20 cm to accelerate the flow from the primary combustion zone 50 to 60 m/sec at the secondary fuel injection plane 58 so as to promote secondary fuel-air mixing. Recent studies have shown that flame will not propagate upstream in a mixture of the secondary fuel and air if the velocity is above 60 m/sec.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
EP82101111A 1981-03-05 1982-02-16 Catalytic combustor having secondary fuel injection for a stationary gas turbine Expired EP0062149B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24071581A 1981-03-05 1981-03-05
US240715 1981-03-05

Publications (2)

Publication Number Publication Date
EP0062149A1 EP0062149A1 (en) 1982-10-13
EP0062149B1 true EP0062149B1 (en) 1985-05-15

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Family Applications (1)

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EP82101111A Expired EP0062149B1 (en) 1981-03-05 1982-02-16 Catalytic combustor having secondary fuel injection for a stationary gas turbine

Country Status (11)

Country Link
EP (1) EP0062149B1 (enrdf_load_stackoverflow)
JP (2) JPS57161425A (enrdf_load_stackoverflow)
AR (1) AR231472A1 (enrdf_load_stackoverflow)
AU (1) AU559254B2 (enrdf_load_stackoverflow)
BR (1) BR8201073A (enrdf_load_stackoverflow)
CA (1) CA1179157A (enrdf_load_stackoverflow)
DE (1) DE3263485D1 (enrdf_load_stackoverflow)
IN (1) IN155658B (enrdf_load_stackoverflow)
IT (1) IT8219960A0 (enrdf_load_stackoverflow)
MX (1) MX160552A (enrdf_load_stackoverflow)
ZA (1) ZA821004B (enrdf_load_stackoverflow)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE8203757L (sv) * 1982-06-17 1983-12-18 Ulf Johansson Forfarande och anordning for forbrenning av flytande brensle
CA1209810A (en) * 1982-10-15 1986-08-19 Paul E. Scheihing Turbine combustor having improved secondary nozzle structure for more uniform mixing of fuel and air and improved downstream combustion
US4726181A (en) * 1987-03-23 1988-02-23 Westinghouse Electric Corp. Method of reducing nox emissions from a stationary combustion turbine
GB8807859D0 (en) * 1988-04-05 1988-05-05 Nordsea Gas Technology Ltd Combination burners
US5161366A (en) * 1990-04-16 1992-11-10 General Electric Company Gas turbine catalytic combustor with preburner and low nox emissions
CA2124069A1 (en) * 1993-05-24 1994-11-25 Boris M. Kramnik Low emission, fixed geometry gas turbine combustor
DE102004005476A1 (de) 2003-02-11 2004-12-09 Alstom Technology Ltd Verfahren zum Betrieb einer Gasturbogruppe
US8141365B2 (en) * 2009-02-27 2012-03-27 Honeywell International Inc. Plunged hole arrangement for annular rich-quench-lean gas turbine combustors

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019316A (en) * 1971-05-13 1977-04-26 Engelhard Minerals & Chemicals Corporation Method of starting a combustion system utilizing a catalyst

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3928961A (en) * 1971-05-13 1975-12-30 Engelhard Min & Chem Catalytically-supported thermal combustion
IT1063699B (it) * 1975-09-16 1985-02-11 Westinghouse Electric Corp Metodo di avviamento di una turbina a gas di grande potenza con un combustore catalitico
US4118171A (en) * 1976-12-22 1978-10-03 Engelhard Minerals & Chemicals Corporation Method for effecting sustained combustion of carbonaceous fuel
GB2040031B (en) * 1979-01-12 1983-02-09 Gen Electric Dual stage-dual mode low emission gas turbine combustion system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019316A (en) * 1971-05-13 1977-04-26 Engelhard Minerals & Chemicals Corporation Method of starting a combustion system utilizing a catalyst

Also Published As

Publication number Publication date
JPS6234141Y2 (enrdf_load_stackoverflow) 1987-08-31
BR8201073A (pt) 1983-01-11
AR231472A1 (es) 1984-11-30
JPS6012071U (ja) 1985-01-26
CA1179157A (en) 1984-12-11
DE3263485D1 (en) 1985-06-20
IN155658B (enrdf_load_stackoverflow) 1985-02-16
AU559254B2 (en) 1987-03-05
EP0062149A1 (en) 1982-10-13
MX160552A (es) 1990-03-22
ZA821004B (en) 1983-02-23
AU8048982A (en) 1982-09-09
JPS57161425A (en) 1982-10-05
IT8219960A0 (it) 1982-03-04

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