JPH018834Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a combustion injection device for a gas turbine combustor, and particularly to a gas turbine which is designed to stabilize the combustion state even when the gas turbine combustor is under low load. Related to improvements in combustion injection devices.

[Technical background of the invention and its problems]

In recent years, gas turbines have been made hotter and larger in order to increase single unit capacity and reduce operating costs per unit output. When increasing the capacity of a gas turbine, it is inevitably necessary to increase the number of fuel units that supply the combustor, and therefore the capacity of the fuel injection device disposed in the combustor must also be increased.

However, the amount of fuel required in each operation mode from the start of the gas turbine to the maximum load differs greatly, and this difference becomes particularly noticeable when the gas turbine capacity is increased.

FIG. 6 shows a gas combustion injection device that has been commonly used up to now, in which fuel gas flows in from a fuel inlet 50, passes through the inside of a housing 51, and is ejected from an injection port 52 provided at the tip. Then, it is mixed with compressor discharge air fed from the swirler 53 and burned inside a combustor (not shown). In the gas fuel injection device having such a configuration, the injection port 5
Since the flow path area of No. 2 is constant, if the above-mentioned required fuel amount differs depending on the operation mode, the following inconvenience will occur. In other words, the above-mentioned injection port flow path area is generally designed based on 100% load, so although good combustion can be obtained at high load or when starting the turbine, at low load the fuel amount decreases. Since the injection port area is the same as when the load is high, the difference between the fuel gas pressure and the combustor internal pressure becomes small, and the injection pressure ratio π becomes smaller than the limit pressure ratio as shown in FIG. In such a situation, combustion becomes unstable and troubles such as combustion vibration and misfire occur.

Conversely, in order to secure sufficient differential pressure for low-flow fuel, the injection port area must be reduced, but in order to increase the fuel flow rate at high loads, the fuel supply pressure must be increased. This has the disadvantage of undesirably increasing the pressure of the plant equipment.

[Purpose of invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a gas fuel injection device for a gas turbine that is capable of sending suitable and stable fuel to a combustor even at a low flow rate of fuel in a low load region. With the goal.

[Summary of the idea]

The present invention includes a housing equipped with a fuel inlet,
a nozzle body that is attached to an opening formed at the end of the housing, has a concave portion formed on its surface, and has a hole provided to pass through the concave portion and the inside of the housing; A throttle valve in which a support part connected to the head of the throttle valve slides within the nozzle body under the elastic force of a spring, and can move forward and backward with respect to the nozzle body by movement of the support part. A slit is formed in the head of the throttle valve and the throttle valve to give a swirling flow to the fuel, and when the load is low, the gas turbine is configured to give a swirling flow to the fuel through the slit and send it to the combustor. It is a gas fuel injection device.

In this configuration, fuel is ejected from the housing into the combustor through a hole provided in the nozzle body and further through a gap formed between a recess provided in the nozzle body surface and the head of the throttle valve. . At this time, a force based on the pressure difference between the fuel supply pressure and the combustor internal pressure acting on the throttle valve head expands and contracts the spring that urges the throttle valve to engage with the nozzle body. Due to the expansion and contraction of this spring, the fuel flow area secured by the gap formed between the recess of the nozzle body and the throttle valve head is small when the fuel flow rate is small, and conversely when the flow rate is large. When it becomes bigger, it changes to become bigger.

In this way, the flow path area changes depending on the size of the fuel flow rate, but even so, at low loads, the differential pressure between the fuel pressure and the pressure inside the combustor is small, so there is no flow of the fuel itself, and this As a result, the degree of combustion within the combustor is uneven, and vibrations occur due to local heating due to local combustion within the combustor and pressure differences between combustion and non-combustion areas.

Even if such a problem occurs, the slit in the throttle valve head provides a swirling flow to the fuel and sends it to the combustor. As a result, even though the differential pressure between the fuel pressure and the pressure inside the combustor is small and the expansion and contraction force of the spring is not utilized, the fuel is given a swirling flow, so the fuel ejected from the nozzle body flows inside the combustor. spread throughout the area.

[Example of idea]

FIG. 1 shows a gas fuel injection device according to an embodiment of the present invention, in which a nozzle body 4 is attached to an opening 3 formed at the end of a housing 2 having a fuel inlet 1. has been done. A concave portion 5 having a concave opening is formed on the surface of the nozzle body 4, and a head 8 of a throttle valve 7, which is slidably supported in the nozzle body 4 via a support portion 6, is housed in the concave portion 5. ing. Further, the nozzle body 4 is provided with a plurality of holes 9 that communicate with the recess 5 and the inside of the housing 2, and a swirler 10 is formed around the entire circumference from the side of the nozzle body 4 toward the inside of the recess 5. has been done. A spring 11 is inserted through the end of the support part 6 of the throttle valve 7 so as to be sandwiched between a stopper 12 fixed to the support part 6 and the nozzle body 4, and a stopper 13 is fixed to the support part 6. The stroke of the throttle valve 7 is limited. In addition, code 1
4 is an O-ring for preventing vibration. Second
The figure is a view taken along the line A-A in FIG. It has a curved shape so that it is delivered to the combustor. Further, the number of these slits 15 is the same as the number of swirlers 10.

In the above configuration, the fuel flowing in from the fuel inlet 1 changes its direction within the housing 2 and passes through the hole 9 of the nozzle body 4, and is further formed between the recess 5 of the nozzle body 4 and the head 8 of the throttle valve 7. The fuel is injected through the gap 16 into a combustor (not shown). When this fuel is injected, it forms a swirling flow along the slit 15 and mixes with the compressed air supplied from the swirler 10. At this time, the flow path area secured by the gap 16 changes based on the differential pressure between the fuel gas supply pressure acting on the throttle valve 7 biased by the spring 11 and the combustor internal pressure. That is, the hole 9 of the nozzle body 4
The fuel passing through the combustor tends to push the throttle valve 7 outward according to the pressure difference between the combustor internal pressure Pcc and its own fuel gas pressure Pgas (Pgas-Pcc). On the other hand, since the movement of the throttle valve 7 is suppressed by the spring 11, a force obtained by multiplying the differential pressure by the pressure-receiving area F of the throttle valve 7 acts on the spring 11, and the spring 11 has an elastic force generated therein. It will expand and contract to balance the above force. That is, if the elastic constant of the spring 11 is k, the displacement Δl of the spring 11 can be determined by the following equation.

Δl=F/k(Pgas-Pcc) =F/k×Pcc×(π-1) ...(1) Here, the injection pressure ratio π=Pgas/Pcc The throttle valve 7 opens and closes according to the displacement of the spring 11. Therefore, the flow area A of the fuel gas secured between the throttle valve 7 and the recess 5 of the nozzle body 4 can be expressed by the following equation using the function f.

A=Amin+f(Δl)...(2) Note that Amin≦A≦Amax...(3) Here, Amin is the minimum value of the flow path area, and in this embodiment, the throttle valve 7 is placed in the recess 5 of the nozzle body 4. When the stopper 13 fixed to the support part 6 of the throttle valve 7 is in contact with the nozzle body 4 (in the state shown in FIG. 1), the area secured by the slit 15, Amax, is the maximum value of A. is the area of (2)
In the equation, the function f varies depending on the inclination angle of the dovetail-shaped portion of the recess 5.

In a gas turbine, as the rotation speed and load increase, the discharge pressure of the compressor increases and the combustor internal pressure Pcc increases. If the above-mentioned injection pressure ratio π is kept at least at a constant value, Δl will increase from equation (1), and therefore the flow path area A will increase from equation (2). This allows the flow rate to be increased.

According to the above configuration, an appropriate pressure difference between the fuel gas pressure Pgas and the combustor internal pressure Pcc can be ensured at each load. Therefore, as shown in FIG. 3, the injection pressure ratio π can be greater than the limit value even under low load conditions.

However, even if the injection pressure ratio π is increased above the limit value, the fuel flow rate is small at low load, so the gap 16 formed between the recess 5 of the nozzle body 4 and the head 8 of the throttle valve 7 is The fuel that passes through it does not flow as calculated, but flows unevenly, causing local combustion.
In this case, since the slit 15 is bored in the head 8, even if the fuel flows unevenly, the slit 15 will give the fuel a swirling flow, and the fuel itself will flow into the combustor while swirling. As a result, the delivered fuel is spread throughout the combustor. In this way, the combustion state of the combustor can be kept stable.

FIG. 4 shows another embodiment in which the side surface of the head 8 of the throttle valve 7 is a flat surface as shown in FIG. The lower surface of the head 8 is brought into contact with the nozzle body 4 so as not to come into contact with the recess 5 and seal the recess 5. In this way, by securing the necessary flow path area over the entire circumference of the head 8 of the throttle valve 7, good mixing with the compressor discharge air can be achieved even when the fuel gas pressure is low, such as during low load. Can be done.

[Effect of idea]

As described above, the present invention biases the throttle valve with a spring to open and close it based on the differential pressure between the fuel gas pressure and the internal pressure of the combustor. Since the slit in the head of the throttle valve is utilized when the fuel cannot be delivered to the desired temperature, the present invention makes it possible to obtain good combustion over a wide load range from low to high loads. Therefore, combustion oscillations do not occur, and it is possible to prevent the inconvenience of the turbine tripping due to combustion oscillations, which is the case with conventional combustion engines.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view of a gas fuel injection device according to an embodiment of the present invention, and FIG. 2 is a line A-A in FIG. 1.
3 is a diagram illustrating the action of the present invention, FIG. 4 is a partially cutaway sectional view showing another embodiment of the present invention, and FIG. 5 is a view taken along the line BB in FIG. 4. A perspective view, FIG. 6 is a partially cutaway sectional view of a conventional gas fuel injection device, and FIG. 7 is a diagram illustrating the operation of the conventional gas fuel injection device. 1... Fuel inlet, 2... Housing, 3...
Opening, 4... Nozzle body, 5... Recess, 6... Support, 7... Throttle valve, 8... Head, 9... Hole, 1
1...Spring, 15...Slit.

Claims (1)

[Scope of utility model registration request] A housing having a fuel inlet, and a nozzle that is attached to an opening formed at an end of the housing, has a concave portion formed on its surface, and has a hole extending through the concave portion and the inside of the housing. A supporting portion connected to the head of the throttle valve housed in the concave portion slides within the nozzle body under the elastic force of a spring, and movement of the supporting portion causes the support portion connected to the head of the throttle valve housed in the recess to slide against the nozzle body. The throttle valve has a slit formed in the head thereof to give a swirling flow to the fuel, and when the load is low, a swirling flow is given to the fuel through the slit. Gas turbine gas fuel injection device that sends fuel to the combustor.