JPH0715266B2 - Fuel injection device for vehicle gas turbine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection nozzle for a gas turbine for a vehicle.

[Conventional technology]

The operating conditions of a gas turbine engine for driving a vehicle fluctuate over a wide range from light load operation such as idling to full load operation that produces the maximum output, so the amount of fuel injected into the combustion chamber also depends on the load fluctuation. Fluctuates over a wide range. Therefore, it is difficult for the fuel injection nozzle having a single fuel injection port to inject the fuel in a good atomization state over the entire flow rate range of the fuel. That is, when the fuel injection port diameter is increased to match the large flow rate side, at light load, when the fuel flow rate is small, the flow velocity at the injection port decreases and fuel atomization cannot be secured. In addition, if the diameter is reduced, the fuel injection amount becomes insufficient on the large flow rate side. Therefore, in a gas turbine engine for a vehicle, a fuel injection nozzle having two independent injection ports of a large size and a small size is used in one main body, as described in JP-A-62-70628. ing. This fuel injection nozzle injects fuel only from the small-diameter injection port (first injection port) out of the above when the fuel injection amount is small in light load operation such as when the engine is idling, and the load is applied to the engine to some extent, When the injection amount exceeds a predetermined value, fuel is also injected from another large-diameter injection port (second injection port), and the required fuel injection amount together with the fuel injection amount from the first injection port. It is designed to achieve the above, and by providing the above-mentioned two large and small injection ports, it is possible to properly atomize the fuel at light load and to reliably supply the required amount of fuel at high load. There is.

[Problems to be Solved by the Invention]

As described above, of the two injection ports of the fuel injection nozzle of the gas turbine engine for a vehicle, the second injection port does not inject fuel during light load such as idling, the load increases, and the fuel flow rate becomes a certain value. When it exceeds the limit, fuel is only injected. However, the fuel injection nozzle is attached to the combustor and is constantly exposed to radiant heat during operation, and when light load operation such as idling continues, fuel is not injected from the second injection port, so the fuel is injected into the injection port. There is a problem that the residual fuel oil is heated to a high temperature and carbonized, and is fixed in the second injection port to block a part or all of the injection port.

The above-mentioned problem of blockage tends to occur particularly when a high-viscosity fuel such as low-quality oil is used, and when the injection port is blocked, not only the fuel supply becomes insufficient during high load operation, but also the fuel supply is the first injection. Since it concentrates on the mouth, the fuel flow rate of the first injection port increases, and the fuel injection speed tends to become excessive. Therefore, the fuel reaches the combustor wall in a liquid state, adheres to the wall surface, burns, and damages the combustor, so that so-called one-sided blowing of fuel is apt to cause meltdown of the combustor.

In view of the above points, an object of the present invention is to provide a fuel injection device that prevents the second injection port from being blocked while ensuring a good atomization state of fuel during light load operation of an engine.

[Means for Solving the Problems]

To achieve the above object, according to the present invention, there is provided a fuel injection nozzle for ejecting a fluid such as air or fuel from the second injection port at the time of light engine load such as idling operation.

That is, in the first embodiment of the present invention, a fuel injection nozzle having a structure in which a small amount of fuel is continuously injected from the second injection port at the time of light load such as idling operation is provided. The fuel is intermittently injected in a pulse form from the second injection port during light load such as operation. Further, in the third embodiment of the present invention, there is provided a fuel injection device which does not inject fuel from the second injection port at the time of light load such as idling operation, but instead injects pressurized air.

[Action]

As described above, by injecting air, fuel, or the like from the second fuel injection port at the time of light load of the engine, the fuel is prevented from staying in the injection port, and the injection port is blocked due to carbonization and sticking of the fuel. Absent.

〔Example〕

Fig. 10 shows a schematic configuration of a two-shaft gas turbine engine for vehicles. This gas turbine engine is a two-shaft type in which a compressor turbine 4 and a power turbine 6 rotate independently, and includes a heat exchanger 2 for improving thermal efficiency. In the figure, the air sucked from the air inlet is compressed by the compressor 1, heated by the exhaust gas in the heat exchanger 2 and then enters the combustor 3, and is mixed with atomized fuel injected from the fuel injection nozzle 8 and burned. To do. The high-temperature and high-pressure combustion gas first drives the compressor turbine 4 to power the compressor 1, and then passes through the variable nozzle 5 and then the power turbine 6
To generate power. Here, the variable nozzle 5 is for changing the distribution of the combustion gas energy between the compressor turbine 4 and the power turbine 6, and automatically adjusts each turbine so as to maintain an optimum operating state according to the load condition. Adjusted. Exhaust gas is from the heat exchanger 2 as described above.
After exhaust heat is applied to the intake air, it is exhausted to the outside from the exhaust outlet. The power generated in the power turbine 6 is decelerated by the reduction mechanism and taken out to the output shaft 7.

Examples of the fuel injection nozzle of the present invention will be described below. FIG. 1 shows the structure of the first embodiment of the fuel injection nozzle of the present invention. The fuel injection nozzle 8 is a mounting case 10 mounted on the wall 9 of the combustor 3, and an inner case inserted therein. 11, an outer nozzle tip 12 having a second ejection port on the lower side thereof, an inner nozzle tip 13 having a first ejection port 13, a branching tip 14, and a distribution valve case in order on the outer nozzle tip 12.
The check valve case 16 is stacked and the union nut 17 is tightened. Then, a valve 19 biased downward by a spring 18 in the distribution valve case 15 is inserted so as to shut off the fuel flow path to the outer nozzle tip 12 at a constant fuel pressure P ₁ or less, while , The fuel flow path to the inner nozzle tip 13 below the distribution valve case 15 is not provided with any valve and is normally open, but the common inlet flow path of these fuel paths has a spring 20 A check valve 21 biased upward by a filter 23 and a filter 23 housed in a filter case 22 are inserted, and pressurized liquid fuel is supplied through a fuel nozzle adapter 24 screwed to the upper end. It is like this.

Combustion, from the air holes 26 provided in the wall of the flame spreader inner cylinder 25,
The high-temperature compressed air compressed by the compressor 1 and heated by the heat exchanger 2 mixes with the fuel spray 27 injected while swirling from the fuel nozzle 8 in the combustor inner cylinder 25, and is ignited by an ignition device (not shown). By
It occurs continuously in the combustion zone 28. At this time, the liquid fuel is pressurized by a fuel pump (not shown), and is supplied from the nozzle adapter 24 to the fuel injection nozzle 8 through the fuel hose.
Supplied within. Then, after passing through the filter 23, the check valve 21 is pushed open to flow down, and the normally open inner nozzle tip is opened.
It is injected into the combustor inner cylinder 25 from the 13th first injection port. When the gas turbine engine is not required to have a high output, the fuel is swirled and injected from only the first injection port of the inner nozzle tip 13 as described above. By operation or the like, the supply pressure of the liquid fuel increases accordingly, the fuel injection amount from the inner nozzle tip 13 increases, and when the pressure exceeds a certain value P ₁ , the valve 19 opens and the outer nozzle tip 12 Is also supplied with fuel, and the fuel injection with a swirl is also performed from the second injection port to increase the combustion amount.

The solid line in FIG. 2 shows the flow rate characteristics of the fuel injection nozzle 8, where P is the pressure of the liquid fuel, G is the flow rate (that is, the injection amount or the combustion amount), and the pressure is P ₁ or less under low load operation. Flow rate is less than or equal to G ₁ , then the inner nozzle tip 13
Although the fuel is injected only from the first injection port of No. 2, the flow rate becomes G ₁ or more in the high load operation where the pressure exceeds P _1, and the fuel injected from the second injection port of the outer nozzle tip 12 also joins the spray 27. To burn.

The pressure P ₁ at which the fuel injection from the second injection port of the outer nozzle tip 12 is started is the spring for urging the valve 19.
Determined by 18, the flow rate G ₁ at that time is the inner nozzle tip
It is determined by the diameter of the 13th injection ports. Here G ₁
Indicates the fuel injection amount required at idling. Also, the broken line in the figure shows the flow rate characteristic of the conventional fuel injection nozzle.

As can be seen from the figure, in the conventional fuel injection nozzle, the second injection port does not open at the time of idling and the second injection port starts to open at a flow rate of G ₂ > G _i , while in the present embodiment, at the time of idling (G = G _i ), the diameter of the first injection port is determined so that the fuel is injected from the second injection port. In a two-shaft gas turbine for vehicles, P ₁ is about 10 to 30 kg / c
It is set in the range of m ² .

As a result of setting the diameter of the first injection port as described above, a small amount of fuel can be injected from the second injection port even during idling operation of the vehicle, and the fuel always flows in the outer nozzle tip, and in the flow path. The fuel is prevented from carbonizing and sticking.

Note that the fuel injection amount may fall below G ₁ during deceleration during operation, in which case the fuel injection from the second injection port is temporarily stopped, but in the two-shaft gas turbine engine, the compressor turbine is large. Since the compressor load is carried, when the fuel injection amount becomes G ₁ or less, the rotation speed drops to the idling rotation speed in a short time. Therefore, the above-mentioned injection suspension period is as short as several seconds, and the injection is restarted immediately, so that problems such as fuel carbonization do not occur. Furthermore, at G _i or less, the fuel injection amount from the second injection port is small, and most of the fuel is injected from the first injection port that has been set to a smaller diameter than before, so the injection speed is low even when idling with a small flow rate. It is larger than that of the above and can secure good atomization.

In the above embodiment, a small amount of fuel is injected from the second injection port even during idling in order to prevent the fuel accumulated in the second injection port from being carbonized and stuck due to the high temperature to block the injection port. However, during cold start of the engine or during warm-up operation, even if fuel remains in the second injection port, there is no risk of carbonization of the fuel because the temperature of the fuel injection nozzle is not high. In such a case, rather than stopping the fuel injection from the second injection port and injecting all the fuel from the first injection port, the fuel injection speed can be increased and fuel atomization can be promoted. It is preferable in terms of engine startability when the engine is running and white smoke and exhaust odor when the engine temperature is low. FIGS. 3 to 5 show an improved example of the first embodiment for the above purpose. In this modified example, during cold start or during warm-up operation, the fuel injection from the second injection nozzle is stopped while the temperature of the fuel injection nozzle is low, engine warm-up is completed, and there is a possibility that white smoke or strange odor of exhaust gas will be generated. When there is no fuel, fuel injection from the second injection port is started. The fuel injection characteristics after completion of warm-up are the same as in the first embodiment. FIGS. 3 and 4 are partial cross-sectional views of the fuel injection nozzle of this improved example, and the parts not shown have exactly the same structure as in FIG. As shown in FIG. 3, in this improvement, the valve 19 for opening and closing the fuel supply passage to the second injection port in the fuel injection nozzle is not only biased by the spring 18 similar to that in FIG. Temperature sensitive member
It is urged by 30 (a disc spring made of bimetal in this modified example). When the temperature of the fuel injection nozzle is low due to insufficient warming up of the engine (when the nozzle temperature is about 80 ° C or less in this modified example), the disc spring 30 has a downward convex shape as shown in FIG. Therefore, the valve 19 is pressed to close the fuel supply path to the second injection port. Therefore, the entire amount of fuel is supplied from the first injection port, the injection speed is increased, and atomization is promoted. However, when the engine warms up and the temperature of the fuel injection nozzle rises and exceeds the set value (about 80 ° C. in this improved example), the disc spring 30 reverses and projects upward as shown in FIG. Since the state is set and the valve 19 is separated from the valve 19, the valve 19 is opened and closed by the fuel pressure and the reaction force of the spring 18 as in the first embodiment. Therefore, in this modified example, as shown in FIG. 5, the characteristics of the fuel injection nozzle are different between when the engine is cold and after warming up. The dotted line in FIG. 5 shows the injection characteristic when the engine is at a low temperature, and the solid line shows the injection characteristic after completion of warm-up.
The injection characteristics after warming up are the same as those shown in FIG.
In the figure, G _fi indicates the fuel injection amount at idling, and G _fs indicates the fuel injection amount at engine start. Also, P _fi and P _fi ′ are G
Fuel pressure after warming up and at low temperature when injecting the flow rate of _fi , and P _fs and P _fs ′ indicate fuel pressure after warming up and at low temperature at the flow rate of G _fs , respectively. As is apparent from the figure, the engine starting fuel pressure P _fs ′ during cold starting is much higher than the pressure P _fs after warming up, and atomization of the fuel is improved, improving engine starting characteristics. Similarly, fuel pressure during idling
P _fi ′ is also higher than P _{fi and} has the effect of reducing exhaust odor at low engine temperatures. Figure A point is a point that opens the valve 19 when the engine low temperature overcomes the biasing force of the disc spring 30 and the spring 18, the combustion remains fuel injected from the fuel pressure P ₂ 'is first injection port at this time of the liquid The pressure is set so as not to melt the burner and reach the wall of the furnace.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present invention, the first embodiment continuously injects a small amount of fuel from the second injection port even when idling, whereas by injecting the fuel in a pulsed manner, the fuel injection speed is achieved even at a small flow rate. To improve the atomization of fuel. In this embodiment, the first injection port
Fuel is supplied to the 45 and the second injection port 46 through independent fuel passages 43 and 44, respectively. Further, the fuel passages 43 and 45 are independently supplied with fuel from the outside via the nozzle adapters 41 and 42, respectively. FIG. 7 is a diagram showing a fuel supply system to the fuel injection nozzle. Fuel tank in figure
The fuel in 31 is pressurized by the fuel pump 32 and supplied to the fuel actuator 33 for the first injection port and the fuel actuator 34 for the second injection port. The fuel actuators 33 and 34 are controlled by the engine electronic control unit 35 (referred to as ECU), and inject fuel from the first and second injection ports 45 and 46 of the fuel injection nozzle 8 via the nozzle adapters 41 and 42, respectively. Have control. Since the fuel injection from the first and second injection ports is individually controlled in this way, the injection characteristics from each injection port can be set arbitrarily. In the present embodiment, when the ECU 35 detects that the fuel flow rate has decreased and the engine is in a light load state such as idling, the fuel actuators 33 and 34 are controlled to set the flow rates required for idling operation to the first and second values. Dispense to the injection port of. Since the fuel injection from each injection port is performed in a pulsed manner, even if the total fuel flow rate is small, the instantaneous flow rate at the injection port becomes very large, the injection speed increases, and fuel atomization improves. 8th
The figure shows an example of distribution of fuel to each injection port, FIG. 8A shows the time change of the injection amount from the first injection port, FIG. 8B shows the time change of the injection amount from the second injection port, FIG. 8C shows the total injection amount from both injection ports, that is, the amount of fuel supplied to the combustion chamber. In this example, the fuel is injected alternately from the first injection port and the second injection port in a pulsed manner to obtain the total flow rate G _N. At this time, the injection of the flow rate G _N1 (g / sec) and the injection time t _N1 (sec) is performed from the first injection port, and the flow rate G _N2 (g / sec) and the injection time t _N2 (of the second injection port). sec) injection is performed, and the total (average) flow rate is G _N = (G _N1 × t _N1 + G _N2 × t _N2 ) /
It is represented by (t _N1 + t _N2 ). Therefore, by appropriately selecting the injection time t _N1 tot _N2 , G _N1 and G _N2 can be set so that the injection speed (fuel atomization) from each injection port is maintained in a good state. Further, in the present embodiment, the distribution of the injection amount to each injection port can be set freely, and in addition to FIG.
Continuous injection may be performed from the injection port, and pulse injection may be performed only from the second injection port. Conversely, continuous injection may be performed from the second injection port and pulse injection may be performed only from the first injection port. You can Further, although the injections from both injection ports do not overlap in FIG. 8, they may be made to overlap at the start and end of both injections. When the fuel injection is performed in pulses as described above,
Actually, the total flow rate does not become a constant value and fluctuates as shown in FIG. 8C, but if the injection times t _N1 and t _N2 are set to short times, the fluctuation of the engine speed does not occur. The fuel injection flow rate G _N1 and G _N2 from each injection port or the injection time
By changing t _N1 , t _N2, or both, it is possible to respond by changing the total fuel flow rate. Further, when the engine load rises and exceeds a predetermined value, fuel is continuously injected from both nozzles as in the conventional case. As described above, according to this embodiment, it is possible to further improve the atomization of the fuel while maintaining the flow of the fuel at the second injection port to prevent the carbonization of the fuel. In this embodiment, 1
Although one fuel injection nozzle is provided with two injection ports, it is naturally possible to provide each injection port on an independent fuel injection nozzle.

Next, a third embodiment of the present invention will be described. First above
In the second embodiment, fuel carbonization in the injection port is prevented by injecting fuel through the second injection port during idling, but in the present embodiment, fuel injection from the second injection port is stopped during idling. Air is ejected from the second ejection port. Therefore, the fuel retained in the second injection port is purged by the air flow, and the fuel does not remain in the injection port. Further, as a result, since all the fuel can be injected from the first injection port, the atomization of the fuel at a light load can be improved. Figure 9 is the third
2 is a fuel system diagram showing the embodiment of FIG.

In this embodiment, as in the second embodiment, the first and second injection ports each have an independent fuel system, and the structure of the fuel injection nozzle is the same as that shown in FIG. Second
An air pipe from a pressurized air supply source 50 is connected via a shutoff valve 51 to the upstream side of a nozzle adapter 46 of a fuel supply system to the injection port. The shutoff valve 51 is opened and closed by the ECU 35.
When the engine load becomes equal to or less than a predetermined value, the ECU 35 stops the fuel actuator 34 for the second injection port to stop the fuel supply to the second injection port and opens the shutoff valve 51 to release the pressurized air supply source 50. Pressurized air is supplied to the second injection port. Nozzle adapter 46 The pressurized air is supplied from the upstream side to the fuel passage to
The fuel remaining in the fuel passage downstream of the nozzle adapter 46 due to the injection from the injection port is jetted from the second injection port by the pressurized air and the inside of the passage is purged, so that the fuel does not remain in the passage and is carbonized. Does not occur. The pressurized air may be continuously injected when the engine load is light, or may be intermittently injected by opening and closing the shutoff valve. It is also possible to perform the air injection for the first fixed time when the light load operation of the engine continues for a long time, and to stop the air injection after the purge is completed.

〔The invention's effect〕

The present invention prevents the fuel from being carbonized and stuck in the injection port to block the injection port by injecting the fluid from the second injection port during the light load operation such as idling as described above. It has the effect of improving atomization of fuel during operation and preventing the generation of exhaust white smoke and exhaust odor.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a fuel injection nozzle according to the present invention, FIG. 2 is a fuel injection characteristic diagram of the same embodiment, and FIGS. 3 and 4 are diagrams showing an improved example of the same embodiment. FIG. 5 is a fuel injection characteristic diagram of an improved example of the above, FIG. 6 is a sectional view showing a second embodiment of the present invention, FIG. 7 is a fuel system diagram of the above embodiment, and FIG. 8 is an embodiment of the above. Showing an example of the fuel injection characteristics of FIG. 9, FIG. 9 is a fuel system diagram showing the third embodiment of the present invention,
FIG. 10 is a diagram showing a schematic configuration of a two-shaft gas turbine for a vehicle. 8 ... Fuel injection nozzle, 12, 46 ... Outer nozzle tip (second
Injection port), 13,45 ... Inner nozzle tip (first injection port), 1
8 ... Spring, 19 ... Valve, 30 ... Bimetal disc spring, 3
1 ... Fuel tank, 32 ... Fuel pump, 33, 34 ... Fuel actuator, 35 ... Engine electronic control unit, 24, 41, 42 ... Nozzle adapter, 43, 44 ... Fuel passage, 50 ... Pressurized air source, 51
… Shut-off valve.

Claims (1)

[Claims] 1. A fuel injection having a small-diameter first injection port that always injects fuel during operation and a large-diameter second injection port that continuously injects fuel when the fuel injection amount is a predetermined value or more. A fuel injection device for a gas turbine for a vehicle, comprising a nozzle, means for detecting a light load operation state such as idling of an engine, and means for injecting a fluid from the second injection port during the light load operation.