CN101688669B - Fuel distributor - Google Patents

Abstract

A fuel distributor (1) is disclosed having a distribution element (18) defining a cavity (3), an inlet opening (4) arranged in the distribution element (18), an inlet opening (4) arranged in the distribution element (18) ), and at least one third opening (6) arranged in the distribution element (18), the cross-section of the at least one third opening (6) is larger than the at least one outlet opening (5 ) section.

Description

fuel dispenser

technical field

The present invention relates to a fuel distributor, in particular a fuel distributor for burners and swirlers.

Background technique

The main purpose of the burner is to mix fuel and air together to obtain a stable and efficient combustion with good flame stability and the smallest possible amount of _NOx emissions. Therefore, the design of the burner must ensure that the proper amounts of fuel and air are introduced into the correct locations within the burner and that these quantities are thoroughly mixed so that complete combustion occurs with a minimum amount of excess air for optimum overall combustion. efficiency.

Compatible with these two burner principles are premixed combustion burners and diffusion flame burners, respectively, where the two burner principles can be combined to take advantage of their respective advantages.

In a premixed combustion burner, the air required for combustion is mixed with the burner fuel before being delivered to the combustion zone. The better the fuel and air are mixed, the fewer hot spots exist with fuel/air ratios that exceed stoichiometric requirements. Since flame temperature is a major factor in _NOx production, the more diluted the fuel in the mixture, the less _NOx is produced.

In diffusion flame burners, the fuel is not mixed with air before the combustion zone, but is delivered as pure fuel into the immediate adjoining of the combustion zone. Diffusion flame burners provide good flame stability. However, the amount of _NOx produced is relatively high.

Low-emissions gas turbine engines typically use a combustor with two modes of operation that includes pilot nozzles that form a diffused flame, and a pilot nozzle that exhausts a fuel/air mixture to form the primary combustion surrounding the diffused flame. Multiple main nozzles for mixed flames. US patent 5901555 describes a conventional gas turbine with main burners divided into groups according to load. When the load on the gas turbine is low, the pilot fuel flow is increased to obtain stable combustion. When the load of the gas turbine is high, the flow of pilot fuel is reduced to reduce the amount of _NOx . Individually controllable fuel lines, valves, plumbing and control logic are required to obtain the correct amount of fuel flow to the pilot and main nozzles, adding to the cost of the engine.

Contents of the invention

It is an object of the present invention to provide an improved fuel dispenser.

This object is achieved by the appended claims. The dependent claims describe advantageous developments and variants of the invention.

An innovative fuel distributor that uses pressure gradients across a combustion system to control the proportion of fuel drawn to different regions of the combustion system. These areas provide pilot fuel at low loads, or better mixing of fuel and air at high loads.

The system includes a chamber with an inlet opening and at least two fuel injection openings. The fuel distributor acts as a proximity burner by virtue of having a larger injection opening in an upstream portion of the fuel distributor cavity with respect to compressor air flow and a smaller injection opening in a downstream portion of the cavity with respect to compressor air flow. chamber pressure feeder.

In an advantageous embodiment of the invention, a flow restrictor is arranged at the inlet opening to balance the flow of fuel through at least one smaller outlet opening and at least one larger third opening, respectively.

In yet another advantageous embodiment, the flow restrictor is adjustable to accommodate the pressure of different fuel types.

Since at low fuel pressure fuel leaves the distributor essentially at the outlet opening exposed to the lowest external air pressure, it is beneficial to use this outlet opening as the pilot fuel injection opening.

For the same reason, it is also beneficial to use as the main fuel injection opening a third opening having a larger cross-sectional area and being exposed to a higher external air pressure.

In an advantageous embodiment, the principle of a fuel distributor is applied to a diffusion flame burner, wherein the fuel distributor has a tubular shape with an outlet opening at the end of the tube facing the combustion chamber and facing the fuel The flow is provided with a third opening upstream of the tube. Under low fuel flow conditions, most of the fuel enters the combustion chamber through the outlet opening. Compressor air may enter the fuel distributor through the third opening, providing partial premixing of fuel and air. As the fuel flow increases and the chamber pressure increases, the fuel will escape through the third opening and mix with the compressor air and enter the combustion chamber.

In another advantageous embodiment, the principle of the fuel distributor is applied to a swirler. The cavity of the fuel distributor is arranged in the swirler floor. The fuel opening and the third opening are arranged in the mixing duct, ie in the channel of the swirler. These openings can be arranged in the swirler floor or in the swirler blades. If arranged in the swirler vanes, the arrangement may be at different heights to improve fuel distribution at the height of the swirler vanes. Smaller fuel outlet openings may be closer to the swirler outlet holes with lower pressure. The larger third opening may be in an upstream portion of the swirler channel having a higher pressure relative to the compressor air flow. The fuel outlet opening serves as a pilot injection opening and the third opening serves as a main fuel injection opening.

In yet another advantageous embodiment, the air pressure drop in the mixing duct or cyclone channel between the outlet opening and the third opening is controlled by combining or diverging the mixing duct or cyclone channel.

With such a fuel distribution system design, _NOx emissions are reduced. This innovative fuel dispenser provides increased premix levels with increased fuel flow. The innovative fuel dispenser even provides some premixing of fuel and air in low flow situations, further reducing _NOx emissions. Additionally, the fuel/air mix in premixing conduits such as swirler channels can be varied with fuel flow, eliminating the need for control valves, reducing cost and increasing reliability.

Description of drawings

The invention will now be further described with reference to the accompanying drawings, in which:

Figure 1 represents an innovative diffusion flame burner at low fuel flow;

Figure 2 represents an innovative diffusion flame burner at high fuel flow;

Figure 3 represents a cyclone;

Figure 4 represents a fuel distributor arranged on a swirler floor with openings in said swirler floor at low fuel flow rates;

Figure 5 represents a fuel distributor arranged on a swirler floor with openings in said swirler floor at high fuel flow rates;

Figure 6 represents a fuel distributor arranged on a swirler base plate, wherein the swirler blades have openings on the sides;

Figure 7 shows swirler vanes corresponding to the fuel distributor of Figure 7;

Figure 8 shows percent mass flow through fuel injection openings as a function of fuel mass flow; and

Figure 9 represents a fuel distributor arranged on a swirler floor, wherein the distributor has openings flanking the swirler vanes and meeting the swirler channels.

Like reference numerals in the figures indicate similar or identical components.

Detailed ways

FIG. 1 shows a schematic diagram of an inventive fuel distributor 1 applied in a diffusion flame burner 2 . The fuel distributor 1 comprises a distribution element 18 defining a chamber 3 having an inlet opening 4 , an outlet opening 5 opposite the inlet opening 4 , and two third openings 6 . The third opening 6 is larger than the outlet opening 5 . The flow restrictor 7 is arranged upstream of the inlet opening 4 with respect to the fuel flow 8 and is dimensioned to give the correct pressure to balance the fuel flow 8 between the outlet opening 5 and the third opening 6 . The pressure P1 at the third opening 6 is greater than the pressure P2 at the outlet opening 5 . When the fuel flow 8 is low, most of the fuel 8 will enter the combustion chamber 9 through the outlet opening 5 . If the fuel flow 8 is low enough, air 10 can enter the chamber 3 through the third opening 6 and partially premix the fuel 8 and air 10 . As the fuel flow 8 increases, the pressure in the chamber 3 increases. When the pressure in chamber 3 is higher than P1 , fuel 8 will overflow third opening 6 as shown in FIG. 2 and mix with air 10 . The fuel/air premix then enters the combustion chamber 9 .

Referring to Figure 3, a swirler 11 of a gas turbine engine is shown. The swirler 11 includes a swirler blade 12 arranged on a swirler blade support portion 13 . The swirler vane 12 can be fixed on the burner head (not shown), and the side of the swirler vane is away from the swirler vane supporting part 13 . Swirler channels 14 are formed between adjacent swirler vanes 12 . The swirler channel 14 extends between a swirler channel inlet opening 15 and a swirler channel outlet opening 16 . The swirler channel 14 consists of the opposite side 16 of the swirler vane 12, the surface of the swirler vane support 13 shown to the burner head (not shown), and to which the swirler vane 12 is secured. defined on the surface of the burner head. The outlet opening 5 and the third opening 6 are arranged in the swirler channel 14 of the swirler blade support 13 .

Referring to Figures 4 and 5, cross-sectional views of the inventive fuel distributor 1 arranged in a swirler vane support 13 are shown. The outlet opening 5 and the third opening 6 open outwards into the cyclone channel 14 . Compressor air 10 enters the swirler channel 14 from the left through the swirler channel inlet opening 15 , wherein the pressure P1 at the inlet opening 15 exceeds the pressure P2 at the swirler channel outlet opening 16 . Figure 4 shows the fuel distributor at low load. Fuel 8 enters chamber 3 of fuel distributor 1 through inlet opening 4 via flow restrictor 7 . The main part of the fuel 8 enters the swirler channel 14 through the outlet opening 5 . Only a small amount of fuel 8 enters the swirler channel 14 through the third opening 6 . This facilitates the supply of pilot fuel to the outlet opening 5 . At very low loads, part of the compressor air 10 entering the swirler channel 14 flows into the chamber 3 through the third opening 6 causing some premixing in the chamber 3 . At high loads, the proportion of fuel 8 entering the swirler channel 14 through the third opening 6 increases, as shown in FIG. 5 . The fuel pressure in the chamber 3 overcomes the pressure at the swirler channel inlet opening 15 and the fuel 8 overflows into the swirler channel 14 mainly through the third opening 6 having a larger cross-sectional area.

Figures 6 and 7 show an alternative arrangement in which the distribution of the fuel flow 8 over the height of the swirler channel 14 can be varied. The chamber 3 of the fuel distributor 1 is also arranged in the swirler vane holder 13 . The outlet opening 5 and the third opening 6 are arranged at different heights of the swirler vanes 12 in the swirler channel 14 . Likewise, the outlet opening 5 has a smaller cross-sectional area and is arranged closer to the lower pressure cyclone channel outlet opening 16, while the third opening 6 has a larger cross-sectional area and is arranged closer to the cyclone channel inlet opening 15, where the pressure is higher than at the outlet opening 16 of the cyclone channel.

Referring to Figure 8, there is shown the percent fuel mass flow through the outlet opening 5 and the third opening 6 as a function of the total fuel mass flow. At low loads (ie low mass flow), fuel mainly flows through the outlet opening 5 . The higher the fuel mass flow, the higher the percentage of fuel flowing through the third opening 6 .

FIG. 9 shows another embodiment of the inventive fuel dispenser 1 . The general layout is similar to the embodiment described in FIG. 6 . The pressure drop of the air 10 between the outlet opening 5 and the third opening 6 in the swirler channel 14 is varied by making the swirler channels 14 join (as shown in Figure 9) or diverge (not shown).

Claims (12)

1. A cyclone (11), comprising: Cyclone blade support part (13); a plurality of swirler blades (12) arranged on the swirler blade support portion (13); a plurality of swirler channels (14) formed by said swirler blades (12) and said swirler blade support portion (13); and A plurality of fuel dispensers (1), each fuel dispenser (1) comprising: - a distribution element (18) defining the cavity (3), - whereby said chamber (3) has an inlet opening (4), at least one outlet opening (5) and at least one third opening (6), - whereby said at least one third opening (6) is arranged in the cavity (3) of the fuel distributor (1), in the upstream part of the corresponding swirler channel (14), said at least one outlet opening ( 5) arranged in said cavity (3), in the downstream part of said respective cyclone channel (14), and - whereby the section of said at least one third opening (6) is larger than the section of said at least one outlet opening (5), Wherein said cavities (3) of said plurality of fuel distributors (1) are arranged in said swirler vane support (13). 2. The swirler (11) according to claim 1, wherein a flow restrictor (7) is arranged upstream of the inlet opening (4) of the respective fuel distributor (1) with respect to the fuel flow (8) , said flow restrictor (7) is dimensioned and configured to balance the fuel flow (8) through said at least one outlet opening (5) and said at least one third opening (6) respectively. 3. The swirler (11) according to claim 2, wherein said flow restrictor (7) of the respective fuel distributor (1) is adjustable. 4. The swirler (11) according to any one of the preceding claims, wherein said at least one outlet opening (5) of the respective fuel distributor (1) is a pilot fuel injection opening. 5. The swirler (11) according to claim 1, wherein said at least one third opening (6) of the respective fuel distributor (1) is a main fuel injection opening. 6. The swirler (11) according to claim 1, wherein the outlet openings (5) of the plurality of fuel distributors (1) are arranged at the downstream end of the swirler channel (14) . 7. The swirler (11) according to claim 1, wherein said third openings (6) of said plurality of fuel distributors (1) are arranged upstream of said swirler channel (14) end. 8. The swirler (11) according to claim 1, wherein said outlet openings (5) and said third openings (6) of said plurality of fuel distributors (1) are arranged in said swirler In the diffuser vane support (13). 9. The swirler (11) according to claim 1, wherein said outlet openings (5) and said third openings (6) of said plurality of fuel distributors (1) are arranged in said swirler into the diffuser vanes (12). 10. The swirler (11) according to claim 9, wherein said outlet openings (5) and said third openings (6) of said plurality of fuel distributors (1) are arranged in said swirler at different heights of flow device blades (12). 11. The swirler (11) according to claim 1, wherein the cross-sectional area of the swirler channel (14) increases in the downstream direction. 12. The swirler (11) according to claim 1, wherein the cross-sectional area of the swirler channel (14) decreases in the downstream direction.

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