EP0760450A2 - Brenner - Google Patents

Brenner Download PDF

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Publication number
EP0760450A2
EP0760450A2 EP19960810523 EP96810523A EP0760450A2 EP 0760450 A2 EP0760450 A2 EP 0760450A2 EP 19960810523 EP19960810523 EP 19960810523 EP 96810523 A EP96810523 A EP 96810523A EP 0760450 A2 EP0760450 A2 EP 0760450A2
Authority
EP
European Patent Office
Prior art keywords
inner part
mixing zone
burner
fuel
flow
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.)
Withdrawn
Application number
EP19960810523
Other languages
German (de)
English (en)
French (fr)
Inventor
Klaus Dr. Döbbeling
Hans Peter Knöpfel
Thomas Dr. Sattelmayer
Peter Dr. Senior
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.)
ABB Asea Brown Boveri Ltd
ABB AB
Original Assignee
ABB Asea Brown Boveri Ltd
Asea Brown Boveri AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ABB Asea Brown Boveri Ltd, Asea Brown Boveri AB filed Critical ABB Asea Brown Boveri Ltd
Publication of EP0760450A2 publication Critical patent/EP0760450A2/de
Withdrawn legal-status Critical Current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 
    • F23C7/00—Combustion apparatus characterised by arrangements for air supply
    • F23C7/002—Combustion apparatus characterised by arrangements for air supply the air being submitted to a rotary or spinning motion
    • 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 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/07002—Premix burners with air inlet slots obtained between offset curved wall surfaces, e.g. double cone burners

Definitions

  • the present invention relates to a burner according to the preamble of claim 1.
  • a cone-shaped burner consisting of several shells, so-called double-cone burner, is known for generating a closed swirl flow in the cone head, which becomes unstable due to the increasing swirl along the cone tip and changes into an annular swirl flow with a backflow zone in the core.
  • Gaseous fuels are preferably injected along the channels formed by the individual adjacent shells, also called air inlet slots, as a result of which the fuel mixes homogeneously with the combustion air flowing in there, before combustion by ignition of the mixture thus formed at the stagnation point of the return flow zone, which functions as a disembodied flame holder fulfilled, is initiated.
  • Liquid fuels are preferably introduced via a central nozzle on the burner head, the evaporation of these fuels taking place within the cone cavity of the burner.
  • the latter ignition takes place under conditions typical of gas turbines at an early stage, i.e. near the central nozzle, which cannot be avoided because the NOx emissions have high values precisely because of this lack of premixing, which then makes it necessary, for example, to inject water.
  • Another problem that has an interdependency with the location of the ignition relates to the inherent risk of a flashback due to the unstable backflow zone due to the location being less than optimal.
  • the invention seeks to remedy this.
  • the invention is based on the object of proposing precautions for a burner of the type mentioned which, in addition to a perfect premixing of the fuels used, with the resultant minimization of the pollutant emissions, a local stabilization of the flame front guaranteed.
  • the burner consists of a section that serves to generate swirl and fuel injection, and a downstream mixing zone, the end of which merges into the actual combustion chamber.
  • the flow from the swirl generation section is seamlessly transferred to the mixing zone.
  • the transition geometry between the two flow zones is given by the fact that the burner essentially consists of two bodies arranged concentrically to one another, the inner part ending in a conical outlet.
  • the annular gap between the inner part and the outer shell is preferred Equipped with several spiral, i.e. sloping planes distributed along the circumference, which bridge the annular gap as helixes, and which serve as swirl generators with a specific swirl angle, which is determined from the relationship between the axial direction and flow direction.
  • the transition between this annular swirl generator and the downstream mixing zone is designed so that there is a steady acceleration of the flow in order to minimize the wall boundary layers and thus the risk of kickback of the flame.
  • the main advantage of the invention can be seen in the fact that the course of the swirl angle within the annular path and the amount of the axial speed can be adjusted independently of one another via the radius of the annular gap and over the cross-sectional area such that, on the one hand, a vortex burst for safe flame stabilization is generated at the burner outlet and, on the other hand, the swirl in the mixing zone is kept very low in order to reliably prevent flashback.
  • Another advantage of the invention can be seen in the fact that a perfect premixing of the introduced fuel can be achieved, be it that a gaseous fuel in the area of the annular gap or shortly downstream of the swirl generator radially inwards, or over the inner part and its tip is injected radially outward, be it that a liquid fuel is injected either at the conical tip of the inner part or after the swirl generator in the tangential direction into the annular gap.
  • Fig. 1 shows a burner 1, which consists of an inner part 2 and an outer shell 3 running concentrically therewith, the two parts mentioned to each other by a cylindrical Annular gap 4 are spaced.
  • the inner part 2 in operative connection with the outer shell 3, insofar as it covers the inner part 2, forms the actual swirl generation section, the operation of which is maintained by a series of flow planes which are spiral, that is to say inclined, that is to say helixes 5.
  • These helixes 5 unwind in the circumferential direction of the inner part 2, and fill the entire annular gap 4 in the radial direction.
  • These helices 5 therefore have the task of swirling the combustion air flow 9 flowing in at the top of the burner 1 along the predetermined path to the mixing zone 7.
  • the swirl angle provided for this purpose ie the angle between the axial direction and the flow direction, is preferably around 30 °. It is also important that the transition between the section in which the swirl is generated and the downstream mixing zone 7 results in a constant acceleration of the combustion air 9, in order to minimize the wall boundary layers and thus the risk of the flame flashing back.
  • the inner part 2 ends in the area of said transition, at about 60% of the total length of the outer shell, in a conical tip 6, in which area the flow from the swirl generator, i.e. from the helixes 5, is seamlessly transferred into the mixing zone 7 becomes. This flow transfer is inherently lossless, in such a way that the immediate formation of a backflow zone at the outlet of the swirl generator is prevented between swirl generator and downstream mixing zone 7.
  • the swirl strength in the swirl generator which is based, among other things, on the geometrical design of the helixes 5, the conical tip 6 and the wall surrounding the mixing zone 7, is selected such that the swirl does not burst in the mixing zone 7, but further downstream at the outlet The same, the length of the mixing zone 7 being dimensioned such that there is a sufficient mixture quality for all types of fuel used.
  • the axial speed profile has a pronounced maximum on the Axis and thereby prevents reignitions in this area, but this axial speed drops towards the wall.
  • steps are taken to increase the speed in the outer area of the mixing zone 7 by making the flow cross section of the mixing zone 7, for example, venturi-shaped, or generally narrowing or narrowing. is constricted (see FIG. 2, item 18).
  • Another way to prevent the flame from reigniting in this area is to provide the mixing zone 7 in the flow and circumferential direction with a number of regularly or irregularly distributed bores of various cross-sections and inflow directions, which are not visible in the figure, through which a quantity of air flows the interior of the mixing section 7 flows, and an increase in speed is indicated along the wall thereof.
  • a combination of the above measures can of course be provided to prevent the risk of the flame reigniting into the mixing zone 7.
  • a front wall 8 closes, which is the starting level of a combustion chamber that cannot be seen, a cross-sectional jump being present between the two flow cross sections. Only at this point does a central backflow zone form, which has the properties of a disembodied flame holder. If a flow-like edge zone forms in this cross-sectional jump during operation, in which vortex detachments occur due to the prevailing negative pressure, this leads to an increased ring stabilization of the backflow zone.
  • the front wall 8 can be widened with openings (not visible) through which an amount of air flows directly into the cross-sectional jump, and there contributes, among other things, that the ring stabilization of the backflow zone is thus strengthened.
  • the generation of a stable return flow zone also has a sufficiently high swirl number, ie the critical swirl number within the corresponding cross section the mixing zone 7 required.
  • the outer shell 3 is provided at a suitable location with nozzles 10, through which a fuel, preferably a gaseous fuel, is introduced into the combustion air 9 flowing along the helixes 5. This introduction of fuel normally forms the main stage of the burner 1.
  • the swirling of the combustion air 9 taking place here also forms a first mixing of the fuel; the final mixture formation then takes place in the mixing zone 7.
  • FIG. 2 shows a section of the burner in the region of the conical tip 6 of the inner part 2.
  • the tip itself serves as a nozzle 11 for injecting a fuel 12, which is preferably a liquid fuel.
  • a fuel 12 which is preferably a liquid fuel.
  • This injection is held in such a way that it turns out to be conical, but the wall of the mixing zone 7 and a constriction 18 provided there should not be wetted thereby.
  • the swirled combustion air flowing into the mixing zone 7 surrounds the injected fuel 12: in the direction of flow in the mixing zone 7, the concentration of the injected fuel 12 is continuously reduced to a mixture in the sense of evaporation thereof. If the combustion air is additionally preheated or, for example, enriched with a recirculated smoke or exhaust gas, this precaution supports the evaporation of the liquid fuel before the mixture flows into the downstream stage.
  • FIG. 3 shows a further injection of a fuel 14 in the region of the conical tip 6 of the inner part 2.
  • This fuel is also preferably a liquid fuel which is to be vaporized along the mixing zone 7 in a known manner.
  • the injection takes place via nozzles 13 which, after the combustion air has generated swirl, act in a tangential direction along the inner part 2 with respect to the annular gap (cf. FIG. 1). This is due to the tangential injection of the fuel 14 in the swirled combustion air increases the evaporation of the fuel within the mixing zone 7.
  • FIG. 4 shows a further variant of injecting a fuel into the burner.
  • the fuel used here is gaseous and is first injected radially inward into the combustion air within the annular gap and / or shortly downstream of the swirl generation (see FIG. 1). This type of injection is symbolized by the arrows 15.
  • an additional fuel feed can be provided, which acts radially outward in the region of the conical tip 6 of the inner part 2, as indicated by the arrow 16.
  • FIG. 5 shows essentially the same burner 1 as has already been described in FIG. 1.
  • a pilot stage 17 with a liquid or gaseous fuel is attached in the center, ie inside the inner part 2, a pilot stage 17 with a liquid or gaseous fuel is attached.
  • This pilot stage then acts from the tapered tip 6 in such a way that the burner can be operated even with a small burner load, for example at approximately 10%, without injecting another fuel, for example as provided in FIG. 1.
  • this pilot stage 17 can be used as a stabilization aid in mixed operation outside the self-stable area of the main stage indicated by the annular gap 4.
  • the caloric parts of pilot level 17 are convective or by impact or. Effusion cooling cooled by part of the combustion air 9.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Nozzles For Spraying Of Liquid Fuel (AREA)
  • Pressure-Spray And Ultrasonic-Wave- Spray Burners (AREA)
  • Spray-Type Burners (AREA)
EP19960810523 1995-08-28 1996-08-08 Brenner Withdrawn EP0760450A2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1995131563 DE19531563A1 (de) 1995-08-28 1995-08-28 Brenner
DE19531563 1995-08-28

Publications (1)

Publication Number Publication Date
EP0760450A2 true EP0760450A2 (de) 1997-03-05

Family

ID=7770554

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19960810523 Withdrawn EP0760450A2 (de) 1995-08-28 1996-08-08 Brenner

Country Status (3)

Country Link
EP (1) EP0760450A2 (ja)
JP (1) JPH09112822A (ja)
DE (1) DE19531563A1 (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10029607A1 (de) * 2000-06-15 2001-12-20 Alstom Power Nv Brenner mit gestufter Vormischgas-Eindüsung
US6769903B2 (en) 2000-06-15 2004-08-03 Alstom Technology Ltd Method for operating a burner and burner with stepped premix gas injection

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016154981A1 (zh) * 2015-04-01 2016-10-06 深圳智慧能源技术有限公司 能够加强气流混合的文丘里燃烧器

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE818072C (de) * 1948-12-05 1951-10-22 Christian Stoll Gasbrenner mit Vormischung, insbesondere fuer Industrieoefen
DE1526020B2 (de) * 1965-06-02 1971-10-21 OFU Ofenbau-Union GmbH, 4000 Düsseldorf Gasbrenner insbesondere fuer schwerzuendbare gase
US4271675A (en) * 1977-10-21 1981-06-09 Rolls-Royce Limited Combustion apparatus for gas turbine engines

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10029607A1 (de) * 2000-06-15 2001-12-20 Alstom Power Nv Brenner mit gestufter Vormischgas-Eindüsung
US6769903B2 (en) 2000-06-15 2004-08-03 Alstom Technology Ltd Method for operating a burner and burner with stepped premix gas injection

Also Published As

Publication number Publication date
JPH09112822A (ja) 1997-05-02
DE19531563A1 (de) 1997-03-06

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