RU2107869C1 - Burner of gas-turbine engine combustion chamber - Google Patents

Abstract

FIELD: combustion chambers of gas-turbine engines working mainly on gaseous fuel. SUBSTANCE: each burner of combustion zone and pilot combustion zone. Combustion process in pilot zone is organized at excess air coefficient of α = 1.2 to 1.4 and in main combustion zone at excess air coefficient of α = 1.8 to 2.0. EFFECT: enhanced efficiency. 2 cl, 2 dwg

Description

 The invention relates to combustion chambers (CS) of gas turbine engines (GTE), operating mainly on gaseous fuel.

 Known devices for air-fuel burners located in the front device (CS) [1], containing axisymmetric blade swirls with fuel nozzles located along their axis. In such a device, fuel from nozzles is fed into the reverse current zone (GFC), which is formed downstream behind the swirler, creating a mixture re-enriched with fuel in it. When such a mixture is burned in the BCP (due to the high temperature and the long residence time of the combustion products in the high temperature zone), nitrogen oxides are formed in large quantities, which, together with the combustion products, leave the gas turbine engine, polluting the environment, which is a drawback of such devices.

 At present, both in our country and abroad, strict restrictions have been imposed on the amount of nitrogen oxides emitted by gas turbine engines.

 Combustion chambers are known in which, in order to reduce the amount of nitrogen oxides, they are carried out with two combustion zones (see, for example, US Pat. No. 3,872,664 and [2]), the combustion process is organized in the first zone with a rich composition of the mixture, but with a low fuel consumption into it (10 - 20%), and in the second zone - with a poor mixture of the rest of the fuel on the combustion products in the first zone.In the second zone, a small amount of nitrogen oxides is formed, however, such combustion chambers are complex, have a lot of weight, which is their disadvantage.

 A device for a fuel-air burner [3] (prototype) is known, in which to reduce the emission of nitrogen oxides it is fed up to 55% of the air going to the compressor station, a lean mixture, which reduces the formation of nitrogen oxides. However, from the duty zone located in the center of the burner, it is difficult to transfer the flame to the duty zone of nearby similar burners, because they are separated by layers of a poor mixture, extending along the periphery of the burners. This makes it difficult to start the combustion chamber, which is a disadvantage of such devices.

 The aim of the invention is to reduce the toxicity of combustion products and ensure reliable start of the combustion chamber.

 This goal is achieved by the fact that in the burner the combustion process is organized simultaneously in two zones. In one zone located on the periphery of the burner, the process of burning low fuel consumption is organized on the "rich" composition of the mixture, and in another, located on the axis of the burner, the process of burning the remaining fuel is organized on the "poor" composition of the mixture.

 The proposed technical solution is at the level of the invention, with novelty and utility.

 The invention is illustrated by examples of structural embodiment shown in FIG. 1 and 2.

 In FIG. 1 shows a longitudinal section of the burner; in FIG. 2 is a cross section of a fuel manifold.

 At the inlet of the burner there is an axisymmetric swirler 1 with an opening 2 along the axis and an annular separator 3 along the height of the blades, which on both sides of it can be installed at different angles relative to the axis of the swirl 1. At the periphery of the swirl 2 there is a fuel manifold 4 connected to the fuel-distributing corner formed by two rows of nozzle holes 5, 6, while the axis of the holes 5 are perpendicular to the axis of the swirler 1, and the axis of the holes 6 are parallel to it. The total area of the holes 6 is made equal to 10 - 20% of the total area of the holes 5, 6.

 Behind the swirler 1 there are two concentrically arranged confuser bushings 7, 8, between which a confuser channel 9 is formed, against the entrance of which there are openings 6. The outer sleeve 8 is made with windows (slit) 10 at the inlet and with a socket at the outlet. Windows 10 can be made on the inner sleeve 7.

 The area of the windows 10 is selected from the conditions for obtaining the coefficient of excess air α in the mixture of channel 9, equal to 1.2 - 1.4. At the exit of the channel 9, an axisymmetric swirl 11 is placed. The annular space behind the bell of the sleeve 8, swirl 11 and the output edge of the sleeve 7 forms a stabilization zone 12.

 For a variant of a burner with separate fuel supply to each of the two rows of openings 5, 6, the cavity of the fuel manifold 2 is divided by a partition 13 into two cavities 14, 15, while the fuel is supplied to each of them via separate fuel supply channels 16, 17.

 The burner is installed in the front device of the flame tube 18 of the combustion chamber.

 The air-fuel burner operates as follows.

 When the combustion chamber is turned on, fuel is supplied to the manifold 4, from which it enters through the nozzle openings 5, 6. In this case, the fuel through the openings 5 is fed across the air flow into the zone behind the swirler 1, where it mixes with the turbulent swirl 1, and forms homogeneous (uniform) air the mixture, which is further along the confuser channel of the sleeve 7 extends beyond its slice. The fuel from the openings 6 is fed into the channel 9, where it is mixed with the air entering through the windows 10, and then through the swirler 11 it enters the stabilization zone 12. The combustible air-fuel mixture with α = 1.2 - 1.4 is ignited from an external source (for example, from the candle), forms the combustion zone on duty, from the flame, which ignites the mixture with α = 1.8 ... 2.0, leaving the nozzle of the sleeve 7, forming the main combustion zone. The process of burning a lean mixture with α = 1.8 - 2.0 in the main zone occurs with a low flame temperature, which is insufficient for the intensive formation of nitrogen oxides. The presence of a hole 2 along the axis of the swirler 1 prevents the formation of a reverse current zone behind it, which reduces the residence time of the combustion products in this zone and, therefore, reduces the formation of nitrogen oxides in the main zone.

 The combustion process in the standby zone occurs at a higher flame temperature, therefore, nitrogen oxides are formed in it, however, a small amount of fuel (10 - 20%) burns in this zone and their concentration, referred to the entire fuel consumption, is small.

 If there are two cavities 14, 15 in the collector (and, accordingly, two flow regulators in the engine system), the fuel is first supplied to the cavity 14 until the optimum mode in the standby zone is reached, and then the fuel is supplied to the cavity 15, i.e. into the main combustion zone, a further increase in the production mode occurs due to an increase in fuel consumption in the main combustion zone.

 The ignition of the air-fuel mixture in the adjacent burners occurs from the flame of the duty zone, the ignition of the mixture in which comes from an external source, which ensures reliable starting of the combustion chamber.

 Our company made a prototype of such burners and tested on a full-size engine (RG-N 1 sb. 6) with positive results, namely, when the fuel consumption in the standby zone was 7-15%, the concentration of nitrogen oxides in the exhaust gases of the engine was 30-40 % less compared to an engine equipped with prototype burners.

 Thus, the use of the proposed design of the air-fuel burner on the combustion chamber of a gas turbine engine allows to reduce the concentration of nitrogen oxides in the exhaust gases of the engine, and therefore, to reduce their toxicity and improve the emission characteristics of the engine.

Claims (2)

 1. The burner of the combustion chamber of a gas turbine engine containing a fuel distributing unit connected to the collector, and an axisymmetric swirl with a confuser sleeve at the outlet, characterized in that the collector is located on the periphery of the swirl, and the fuel distributing unit is formed by two rows of nozzle openings, while the axis of the openings of the first row directed perpendicular to the swirl axis, and the axis of the second row parallel to it and facing the inlet of the confuser channel formed by the inner and outer confuser bushings, the latter of which has windows at the inlet and funnel outlet, wherein the outlet channel is provided with a swirler axisymmetric.

 2. The burner according to claim 1, characterized in that the cavity of the fuel manifold is divided by a partition into two cavities so that one of them communicates with the nozzle openings of one row and the other with the openings of the second row.

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