EA039073B1 - Double-tier burner - Google Patents

Abstract

The invention relates to burners of gas turbine units (GTU) and gas turbine engines (GTE), in particular to double-tier burners designed to stabilize the discrete-zone burning with small amount of toxic substances. The main problems for creation of a burner device for low-emission combustion chambers are achievement of high quality atomization and efficient mix of fuel with air flow, and also arrangement of burning in the area of “lean” mixtures. Due to the complexity of processes running in real devices and the absence of convenient mathematical models to describe them, this problem has not been solved yet. The use of chambers where combustion is carried out in two zones is one of the methods for reducing the amount of nitrogen oxide toxic emissions by the GTU combustion chambers and GTE. These zones can be serial and parallel, then they are called tiered. They reduce the length of combustion chamber, but enlarge the dimensions in radial direction. There are principal (“lean”) and auxiliary zones. Different zones work in various modes of the device operation. The discharge of toxic emissions can be controlled by managing the zone operation. This ensures the reduction of nitrogen oxides under severe conditions and in idle run modes. The task of the invention proposed is to create an efficient, cost effective and industrially applicable, easily controlled double-tier burner with low toxic emissions in the exhaust gas. The double-tier burner includes: internal and external tiers, a cylinder-shaped casing 1, fuel pipe for liquid 2 and gas 14 fuel, holes 3 and 11, an inlet swirler 4 for air supply to the burner, a chamber for gas 5, a conical fairing 7, a flap 13, a nozzle 9, blades 8 of the second (external) tier, which are made hollow and mobile relative to a pipe 6 (Fig. 1) or 15 (Fig. 2), which is fitted with slots 16.

Description

The invention relates to burners of gas turbine plants (GTU) and gas turbine engines (GTE), in particular to two-tier burners made with the possibility of stabilizing discrete-zone combustion with a small amount of toxic substances.

The main problems in creating a burner device for low-emission combustion chambers are the achievement of high-quality atomization and efficient mixing of fuel with an air flow, as well as the organization of combustion in the area of lean mixtures. Due to the complexity of the processes occurring in real devices, and the absence of suitable mathematical models for their description, this problem has not yet been solved.

One of the ways to reduce the harmful emissions of nitrogen oxides from the combustion chambers of GTU and GTE is the use of chambers in which combustion occurs in two zones. Zones can be sequential and parallel, then they are called tiered. They shorten the length of the combustion chamber but increase the radial dimensions. There are main (poor) and auxiliary zones. Different zones work in different modes of the device. By controlling the operation of zones, you can regulate the output of toxic emissions. This ensures the reduction of nitrogen oxides in stressed and idle modes.

Known is a combustion chamber burner containing an auxiliary central burner and a main external burner in the form of an air swirler with hollow blades and slots in the trailing edges for dispensing fuel (patent RU 2170391 C1, IPC F23R 3/14, published 10.07.2001).

The disadvantage of the known device is the lack of uniformity of the fuel-air mixture and a decrease in the quality of fuel combustion, respectively, a large amount of toxic substances.

The closest to the invention in technical essence is a two-tier burner with gas recirculation, comprising a housing, a nozzle, and a coaxially mounted pipe in the housing, one end of which is closed by a conical fairing of a fuel-air swirler. A swirler with blades is concentrically installed on the pipe (patent KZ U 3369, IPC F23D 14/24, published on November 16, 2018, bull. No. 43).

This useful model improves the quality of fuel combustion and allows working on two types of fuel at the same time, however, it has a number of such disadvantages as the complication of the controllability of the combustion process and an uneven temperature field.

The objective of the present invention is to provide an efficient, cost-effective and industrially applicable, easily adjustable double-deck burner with low toxic substances in the exhaust gases.

The technical result is an increase in intensification, a range of stable and efficient combustion, a decrease in the formation of nitrogen oxides. When operating a two-tier burner, it is possible to regulate the recirculation of gases, as well as to ensure a high completeness of combustion due to the second tier.

To achieve the technical result, a two-tier burner of a combustion chamber containing a housing, inlet and outlet swirlers from blades, pipes for feeding fuel and spraying, a mixing chamber, according to the invention, is characterized in that the profiled blades of the outer tier are hollow and moveable relative to the axis of attachment, with the possibility of changing angle of installation, and the inner tier is made movable along the axis of the burner, and slots are made in the streamlined cone for the flow of recirculation gases to the outlet vane register, the inlet swirler is also divided in height into three parts, moreover, in the upper and lower parts of the blades are profiled and the swirl angles are coordinated with angles of installation and twist on the outlet blades of the tiers.

The invention is illustrated by drawings. FIG. 1 shows a cross-sectional view of a double-deck burner and FIG. 2 shows an adjustable vane, where

- frame;

- movable fuel tube;

- hole for liquid fuel;

- blade inlet swirler;

- gas chamber;

- hole;

- conical fairing;

- rotary scapula;

- nozzle;

- annular channel;

- hole;

- support or valve;

- flap;

- gas supply tube;

- supply of gaseous fuel axially in each blade;

- slots.

A two-tier burner consists of an inner and an outer tier, containing a housing 1 in the form of a cylinder 1 039073, a fuel pipe for liquid 2 and gaseous 14 fuel, holes 3 and 11, an inlet swirler 4 for air entering the burner, a chamber for gas 5, conical fairing 7, flap 13, nozzle 9, blades 8 of the second (outer) tier, which are hollow and movable relative to pipe 6 (Fig. 1) or 15 (Fig. 2) having slots 16.

The two-tier burner operates as follows: liquid fuel is supplied to the swirling air flow coming from the inlet vane swirler 4 through holes 3 and 11, and gaseous fuel is supplied through hole 6 along axis 15 (Fig. 2). The resulting air-fuel mixture passes through the annular channels 10 and is thrown into the combustion zone in three streams, and two streams are additionally twisted in the annular blades 8, which contributes to the intensification of the combustion process.

The burner is designed to operate both on one type of fuel and for co-firing liquid and gaseous fuels. In this case, the following operating modes are possible: the burner simultaneously burns gaseous and liquid fuel. In this case, the fuels are supplied through holes 3, 11, 6, or, with the conical fairing 7 pushed into the extreme left position, through holes 6 and 11. In the first case, both gaseous and liquid fuels are mixed within the burner and to the outlet from The burner produces a multiphase combustible mixture of an average composition. In the second case, flows of a combustible mixture are formed in the burner, which burn in the form of independent torches, and the external torch is additionally heated by under-vaporized liquid fuel. As a result, the length of the combustion zone along the central cavity of the combustion chamber is shortened. The combined supply of gaseous and liquid fuels to the burner is especially effective when degraded grades are used as the main liquid fuel. The use of gaseous fuel in conjunction with liquid fuel is also advisable to increase the reliability of ignition of the combustion chamber, especially during cold engine starts. When using a low-grade liquid fuel with a reduced value of the calorific value, the supply of a high-calorific value gas to the burner simultaneously ensures an increase in the final gas temperature, and helps to reduce the release of nitrogen oxides and other toxic components from the flare zones.

Adjustment by shifting the central cone of the blade 8, the inner tier, ensures uniform distribution of air and the combustible mixture over the burner cross section, an increase in the excess air ratio flowing through channel 10 adjacent to the fairing 7, since otherwise (in the absence of adjustment) the bulk air under the action of centrifugal forces enters the other two channels 10. And the regulation of the combustion process by changing the angle of installation of the blade 8 has a positive effect on the characteristics of the burner. Gas enters through the tube 14 into the cavity 5 of the gas supply chamber, through the hole 6 the gas enters the axial tubes 15 of the hollow blade 8. In the hollow blade (Fig. 2), air enters through the slots 16 in the leading edge, and a fuel-air mixture of gas is prepared in the blade. air, with α = 0.2-0.4. To further reduce NO _x when burning degraded liquid fuels, hot combustion products are recirculated through flaps 13 to vanes 8.

Thus, the claimed multi-level burner design with the possibility of axial movement of its inner contour allows you to adjust the parameters of the flame and improve the total thermohydraulic and operational parameters of the combustion chamber. At the same time, the starting and partial modes of operation of the combustion chamber are characterized by a shortened torch, and the main and forced modes, among other things, are characterized by a more uniform flame structure, which predetermines the equalization of temperatures in the firing plane. The latter helps to reduce emissions of nitrogen oxides and other toxic components with gases leaving the chamber. In general, the range of stable operation of the combustion chamber is also expanding, and due to a more complete filling of the flame tube section with a torch and a reduction in the total length of the torch, it becomes legitimate to reduce the length of the combustion chamber (decrease its weight) and increase the heat intensity of the structure.

According to preliminary estimates, the proposed two-tiered combustion process organization allows to reduce the NOx emission index for gas turbines by 20%.

At the same time, the proposed device makes it possible to solve the following number of requirements: high combustion efficiency in all operating modes, maximum non-uniformity of the temperature field at the exit from the combustion chamber below 25%, reliable ignition and stable operation (without flame outbursts and vibration combustion) with a large change in the total excess air ratio.

The proposed two-tier burner allows to obtain, in comparison with existing devices, better preliminary mixing of fuel with air, more stable combustion due to the use of microflame combustion, in relation to spontaneous ignition of the fuel.

The developed invention is more resistant to breakthroughs and breakdowns of the flame, vibration combustion, allows to obtain a high combustion efficiency, a significant reduction in the emission of nitrogen oxides in the combustion chambers of the GTU.

The given example is presented to illustrate the claimed invention in the most illustrative form and does not exhaust all possible options for its application.

Claims (1)

A two-tier combustion chamber burner containing a housing, inlet and outlet swirlers from the blades, pipes for feeding fuel and spraying, a mixing chamber, according to the invention, is characterized in that the profiled blades of the outer tier are hollow and movable relative to the fixing axis, with the possibility of changing the angle of installation, and the inner tier is made movable along the axis of the burner, and slots are made in the streamlined cone for the recirculation gases to flow to the outlet vane register, the inlet swirler is also divided in height into three parts, moreover, in the upper and lower parts of the blades are profiled and the swirl angles are coordinated with the angles of installation and swirl on the exit blades of the tiers.